The document summarizes research on the polarizability of donors in spherical gallium arsenide (GaAs) quantum dots (QDs) under an applied electric field. The author uses an effective mass approximation and variational method to calculate:
1) The binding energy of donors at different positions within the QD and as a function of QD size.
2) The polarizability of donors in the QD under an applied electric field. The polarizability is found to be several orders of magnitude higher than hydrogen atoms.
3) The results agree with previous theoretical studies. The binding energy increases as QD size decreases.
International Journal of Computational Engineering Research (IJCER) is dedicated to protecting personal information and will make every reasonable effort to handle collected information appropriately. All information collected, as well as related requests, will be handled as carefully and efficiently as possible in accordance with IJCER standards for integrity and objectivity.
Quantum-Gravity Thermodynamics, Incorporating the Theory of Exactly Soluble Active Stochastic Processes, with Applications
by Daley, K.
Published in IJTP in 2009. http://adsabs.harvard.edu/abs/2009IJTP..tmp...67D
Heat Capacity of BN and GaN binary semiconductor under high Pressure-Temperat...IOSR Journals
In this paper, we have calculated the molar heat capacity for cubic zinc blende (cZB) BN and GaN binary semiconductors at high pressure-temperature (PT). For the calculation of heat capacity, we firstly obtained the Debye temperature (ϴD) variation with temperature and at higher temperature it becomes constant with temperature in quasi-harmonic approximation limits. We have also calculated the static Debye temperature (ϴD) from elastic constant for the both BN and GaN binary semiconductors. The elastic constants are calculated from the energy-strain relation using plane wave method in DFT approach. All the calculated results are well consistence with experimental and reported data
Lecture 6: Introduction to Quantum Chemical Simulation graduate course taught at MIT in Fall 2014 by Heather Kulik. This course covers: wavefunction theory, density functional theory, force fields and molecular dynamics and sampling.
International Journal of Computational Engineering Research (IJCER) is dedicated to protecting personal information and will make every reasonable effort to handle collected information appropriately. All information collected, as well as related requests, will be handled as carefully and efficiently as possible in accordance with IJCER standards for integrity and objectivity.
Quantum-Gravity Thermodynamics, Incorporating the Theory of Exactly Soluble Active Stochastic Processes, with Applications
by Daley, K.
Published in IJTP in 2009. http://adsabs.harvard.edu/abs/2009IJTP..tmp...67D
Heat Capacity of BN and GaN binary semiconductor under high Pressure-Temperat...IOSR Journals
In this paper, we have calculated the molar heat capacity for cubic zinc blende (cZB) BN and GaN binary semiconductors at high pressure-temperature (PT). For the calculation of heat capacity, we firstly obtained the Debye temperature (ϴD) variation with temperature and at higher temperature it becomes constant with temperature in quasi-harmonic approximation limits. We have also calculated the static Debye temperature (ϴD) from elastic constant for the both BN and GaN binary semiconductors. The elastic constants are calculated from the energy-strain relation using plane wave method in DFT approach. All the calculated results are well consistence with experimental and reported data
Lecture 6: Introduction to Quantum Chemical Simulation graduate course taught at MIT in Fall 2014 by Heather Kulik. This course covers: wavefunction theory, density functional theory, force fields and molecular dynamics and sampling.
Lecture 5: Introduction to Quantum Chemical Simulation graduate course taught at MIT in Fall 2014 by Heather Kulik. This course covers: wavefunction theory, density functional theory, force fields and molecular dynamics and sampling.
Lecture 2: Introduction to Quantum Chemical Simulation graduate course taught at MIT in Fall 2014 by Heather Kulik. This course covers: wavefunction theory, density functional theory, force fields and molecular dynamics and sampling.
Analytical, Numerical and Experimental Validation of Coil Voltage in Inductio...ijeljournal
This paper presents, mathematical model of induction heating process by using analytical and numerical methods. In analytical method, series equivalent circuit (SEC) is used to represent induction coil and work piece. Induction coil and workpiece parameters (resistance and reactance) are calculated by standard formulas along with Nagaoka correction factors and Bessel functions. In Numerical method, magnetic vector potential formulation is done and finite element method (FEM) is used to solve the field equations. Analytically and numerically computed parameters such as equivalent coil resistance, reactance, coil voltage, work piece power are compared and found that they are in good agreement. Analytically and numerically obtained coil voltages at different frequencies are validated by experimental results. This mathematical model is useful for coil design and optimization of induction heating process.
Analytical, Numerical and Experimental Validation of Coil Voltage in Inductio...ijeljournal
This paper presents, mathematical model of induction heating process by using analytical and numerical methods. In analytical method, series equivalent circuit (SEC) is used to represent induction coil and work piece. Induction coil and workpiece parameters (resistance and reactance) are calculated by standard formulas along with Nagaoka correction factors and Bessel functions. In Numerical method, magnetic vector potential formulation is done and finite element method (FEM) is used to solve the field equations. Analytically and numerically computed parameters such as equivalent coil resistance, reactance, coil voltage, work piece power are compared and found that they are in good agreement. Analytically and numerically obtained coil voltages at different frequencies are validated by experimental results. This mathematical model is useful for coil design and optimization of induction heating process.
Analytical, Numerical and Experimental Validation of Coil Voltage in Inductio...ijeljournal
This paper presents, mathematical model of induction heating process by using analytical and numerical
methods. In analytical method, series equivalent circuit (SEC) is used to represent induction coil and work
piece. Induction coil and workpiece parameters (resistance and reactance) are calculated by standard
formulas along with Nagaoka correction factors and Bessel functions. In Numerical method, magnetic
vector potential formulation is done and finite element method (FEM) is used to solve the field equations.
Analytically and numerically computed parameters such as equivalent coil resistance, reactance, coil
voltage, work piece power are compared and found that they are in good agreement. Analytically and
numerically obtained coil voltages at different frequencies are validated by experimental results. This
mathematical model is useful for coil design and optimization of induction heating process.
Analytical, Numerical and Experimental Validation of Coil Voltage in Inductio...ijujournal
This paper presents, mathematical model of induction heating process by using analytical and numerical methods. In analytical method, series equivalent circuit (SEC) is used to represent induction coil and work piece. Induction coil and workpiece parameters (resistance and reactance) are calculated by standard formulas along with Nagaoka correction factors and Bessel functions. In Numerical method, magnetic
vector potential formulation is done and finite element method (FEM) is used to solve the field equations. Analytically and numerically computed parameters such as equivalent coil resistance, reactance, coil voltage, work piece power are compared and found that they are in good agreement. Analytically and
numerically obtained coil voltages at different frequencies are validated by experimental results. This mathematical model is useful for coil design and optimization of induction heating process.
Hysteresis Loops for Magnetoelectric Multiferroics Using Landau-Khalatnikov T...IJECEIAES
We present a theoretical discussion of the hysteresis in magnetoelectric multiferroics with bi-quadratic magnetoelectric coupling. The calculations were performed by employing Landau-Khalatnikov equation of motion for both the ferroelectric and ferromagnetic phase, then solve it simultaneously. In magnetoelectric, we obtain four types of hysteresis: ferroelectric hysteresis, ferromagnetic hysteresis and two types of cross hysteresis (electric field versus magnetization and magnetic field versus electric polarization). The cross hysteresis has butterfly shape which agree with the result from the previous research. It can also be seen from that hysteresis, that magnetization / electric polarization can not be flipped into the opposite direction using external electric / magnetic field when the magnetoelectric coupling is bi-quadratic type. Overall, the result shows that LandauKhalatnikov equation is able to approximate hysteresis loops in multiferroics system.
The Interaction between Load Circuits and Decision of Frequency for Efficient ...IJECEIAES
This paper derives an expression of efficiency of wireless power transfer on a situa- tion that there are two devices towards one AC power supply. The interaction between a power supply and load is paid attention on a conventional wireless power transfer system, in contrast, the interaction between loads must be taken account of on the situation too. This is attributed to a possibility that a load disturbs the energy transmitted from a power supply to another load. Moreover each load needs different frequency of power supply for the ideal transfer since they have different natural frequencies on many situations. This paper models a circumstance that there are a power supply and two loads with a state space equation, and proposes how to decide a frequency of power supply to realize efficient transfer for each load.
This is the plenary talk given by Prof Shyue Ping Ong at the 57th Sanibel Symposium held on St Simon's Island in Georgia, USA.
Abstract: Powered by methodological breakthroughs and computing advances, electronic structure methods have today become an indispensable toolkit in the materials designer’s arsenal. In this talk, I will discuss two emerging trends that holds the promise to continue to push the envelope in computational design of materials. The first trend is the development of robust software and data frameworks for the automatic generation, storage and analysis of materials data sets. The second is the advent of reliable central materials data repositories, such as the Materials Project, which provides the research community with efficient access to large quantities of property information that can be mined for trends or new materials. I will show how we have leveraged on these new tools to accelerate discovery and design in energy and structural materials as well as our efforts in contributing back to the community through further tool or data development. I will also provide my perspective on future challenges in high-throughput computational materials design.
Superconductivity and Spin Density Wave (SDW) in NaFe1-xCoxAsEditor IJCATR
A model is presented utilizing a Hamiltonian with equal spin singlet and triplet pairings based on quantum field theory and
green function formalism, to show the correlation between the superconducting and spin density wave (SDW) order parameters. The
model exhibits a distinct possibility of the coexistence of superconductivity and long-range magnetic phase, which are two usually
incompatible cooperative phenomena. The work is motivated by the recent experimental evidences on high-TC superconductivity in
the FeAs-based superconductors. The theoretical results are then applied to show the coexistence of superconductivity and spin density
wave (SDW) in NaFe1-xCoxAs.
Lecture 3: Introduction to Quantum Chemical Simulation graduate course taught at MIT in Fall 2014 by Heather Kulik. This course covers: wavefunction theory, density functional theory, force fields and molecular dynamics and sampling.
Welcome to International Journal of Engineering Research and Development (IJERD)IJERD Editor
journal publishing, how to publish research paper, Call For research paper, international journal, publishing a paper, IJERD, journal of science and technology, how to get a research paper published, publishing a paper, publishing of journal, publishing of research paper, reserach and review articles, IJERD Journal, How to publish your research paper, publish research paper, open access engineering journal, Engineering journal, Mathemetics journal, Physics journal, Chemistry journal, Computer Engineering, Computer Science journal, how to submit your paper, peer reviw journal, indexed journal, reserach and review articles, engineering journal, www.ijerd.com, research journals,
yahoo journals, bing journals, International Journal of Engineering Research and Development, google journals, hard copy of journal
International Journal of Engineering Research and Development (IJERD)IJERD Editor
journal publishing, how to publish research paper, Call For research paper, international journal, publishing a paper, IJERD, journal of science and technology, how to get a research paper published, publishing a paper, publishing of journal, publishing of research paper, reserach and review articles, IJERD Journal, How to publish your research paper, publish research paper, open access engineering journal, Engineering journal, Mathemetics journal, Physics journal, Chemistry journal, Computer Engineering, Computer Science journal, how to submit your paper, peer reviw journal, indexed journal, reserach and review articles, engineering journal, www.ijerd.com, research journals,
yahoo journals, bing journals, International Journal of Engineering Research and Development, google journals, hard copy of journal
Lecture 5: Introduction to Quantum Chemical Simulation graduate course taught at MIT in Fall 2014 by Heather Kulik. This course covers: wavefunction theory, density functional theory, force fields and molecular dynamics and sampling.
Lecture 2: Introduction to Quantum Chemical Simulation graduate course taught at MIT in Fall 2014 by Heather Kulik. This course covers: wavefunction theory, density functional theory, force fields and molecular dynamics and sampling.
Analytical, Numerical and Experimental Validation of Coil Voltage in Inductio...ijeljournal
This paper presents, mathematical model of induction heating process by using analytical and numerical methods. In analytical method, series equivalent circuit (SEC) is used to represent induction coil and work piece. Induction coil and workpiece parameters (resistance and reactance) are calculated by standard formulas along with Nagaoka correction factors and Bessel functions. In Numerical method, magnetic vector potential formulation is done and finite element method (FEM) is used to solve the field equations. Analytically and numerically computed parameters such as equivalent coil resistance, reactance, coil voltage, work piece power are compared and found that they are in good agreement. Analytically and numerically obtained coil voltages at different frequencies are validated by experimental results. This mathematical model is useful for coil design and optimization of induction heating process.
Analytical, Numerical and Experimental Validation of Coil Voltage in Inductio...ijeljournal
This paper presents, mathematical model of induction heating process by using analytical and numerical methods. In analytical method, series equivalent circuit (SEC) is used to represent induction coil and work piece. Induction coil and workpiece parameters (resistance and reactance) are calculated by standard formulas along with Nagaoka correction factors and Bessel functions. In Numerical method, magnetic vector potential formulation is done and finite element method (FEM) is used to solve the field equations. Analytically and numerically computed parameters such as equivalent coil resistance, reactance, coil voltage, work piece power are compared and found that they are in good agreement. Analytically and numerically obtained coil voltages at different frequencies are validated by experimental results. This mathematical model is useful for coil design and optimization of induction heating process.
Analytical, Numerical and Experimental Validation of Coil Voltage in Inductio...ijeljournal
This paper presents, mathematical model of induction heating process by using analytical and numerical
methods. In analytical method, series equivalent circuit (SEC) is used to represent induction coil and work
piece. Induction coil and workpiece parameters (resistance and reactance) are calculated by standard
formulas along with Nagaoka correction factors and Bessel functions. In Numerical method, magnetic
vector potential formulation is done and finite element method (FEM) is used to solve the field equations.
Analytically and numerically computed parameters such as equivalent coil resistance, reactance, coil
voltage, work piece power are compared and found that they are in good agreement. Analytically and
numerically obtained coil voltages at different frequencies are validated by experimental results. This
mathematical model is useful for coil design and optimization of induction heating process.
Analytical, Numerical and Experimental Validation of Coil Voltage in Inductio...ijujournal
This paper presents, mathematical model of induction heating process by using analytical and numerical methods. In analytical method, series equivalent circuit (SEC) is used to represent induction coil and work piece. Induction coil and workpiece parameters (resistance and reactance) are calculated by standard formulas along with Nagaoka correction factors and Bessel functions. In Numerical method, magnetic
vector potential formulation is done and finite element method (FEM) is used to solve the field equations. Analytically and numerically computed parameters such as equivalent coil resistance, reactance, coil voltage, work piece power are compared and found that they are in good agreement. Analytically and
numerically obtained coil voltages at different frequencies are validated by experimental results. This mathematical model is useful for coil design and optimization of induction heating process.
Hysteresis Loops for Magnetoelectric Multiferroics Using Landau-Khalatnikov T...IJECEIAES
We present a theoretical discussion of the hysteresis in magnetoelectric multiferroics with bi-quadratic magnetoelectric coupling. The calculations were performed by employing Landau-Khalatnikov equation of motion for both the ferroelectric and ferromagnetic phase, then solve it simultaneously. In magnetoelectric, we obtain four types of hysteresis: ferroelectric hysteresis, ferromagnetic hysteresis and two types of cross hysteresis (electric field versus magnetization and magnetic field versus electric polarization). The cross hysteresis has butterfly shape which agree with the result from the previous research. It can also be seen from that hysteresis, that magnetization / electric polarization can not be flipped into the opposite direction using external electric / magnetic field when the magnetoelectric coupling is bi-quadratic type. Overall, the result shows that LandauKhalatnikov equation is able to approximate hysteresis loops in multiferroics system.
The Interaction between Load Circuits and Decision of Frequency for Efficient ...IJECEIAES
This paper derives an expression of efficiency of wireless power transfer on a situa- tion that there are two devices towards one AC power supply. The interaction between a power supply and load is paid attention on a conventional wireless power transfer system, in contrast, the interaction between loads must be taken account of on the situation too. This is attributed to a possibility that a load disturbs the energy transmitted from a power supply to another load. Moreover each load needs different frequency of power supply for the ideal transfer since they have different natural frequencies on many situations. This paper models a circumstance that there are a power supply and two loads with a state space equation, and proposes how to decide a frequency of power supply to realize efficient transfer for each load.
This is the plenary talk given by Prof Shyue Ping Ong at the 57th Sanibel Symposium held on St Simon's Island in Georgia, USA.
Abstract: Powered by methodological breakthroughs and computing advances, electronic structure methods have today become an indispensable toolkit in the materials designer’s arsenal. In this talk, I will discuss two emerging trends that holds the promise to continue to push the envelope in computational design of materials. The first trend is the development of robust software and data frameworks for the automatic generation, storage and analysis of materials data sets. The second is the advent of reliable central materials data repositories, such as the Materials Project, which provides the research community with efficient access to large quantities of property information that can be mined for trends or new materials. I will show how we have leveraged on these new tools to accelerate discovery and design in energy and structural materials as well as our efforts in contributing back to the community through further tool or data development. I will also provide my perspective on future challenges in high-throughput computational materials design.
Superconductivity and Spin Density Wave (SDW) in NaFe1-xCoxAsEditor IJCATR
A model is presented utilizing a Hamiltonian with equal spin singlet and triplet pairings based on quantum field theory and
green function formalism, to show the correlation between the superconducting and spin density wave (SDW) order parameters. The
model exhibits a distinct possibility of the coexistence of superconductivity and long-range magnetic phase, which are two usually
incompatible cooperative phenomena. The work is motivated by the recent experimental evidences on high-TC superconductivity in
the FeAs-based superconductors. The theoretical results are then applied to show the coexistence of superconductivity and spin density
wave (SDW) in NaFe1-xCoxAs.
Lecture 3: Introduction to Quantum Chemical Simulation graduate course taught at MIT in Fall 2014 by Heather Kulik. This course covers: wavefunction theory, density functional theory, force fields and molecular dynamics and sampling.
Welcome to International Journal of Engineering Research and Development (IJERD)IJERD Editor
journal publishing, how to publish research paper, Call For research paper, international journal, publishing a paper, IJERD, journal of science and technology, how to get a research paper published, publishing a paper, publishing of journal, publishing of research paper, reserach and review articles, IJERD Journal, How to publish your research paper, publish research paper, open access engineering journal, Engineering journal, Mathemetics journal, Physics journal, Chemistry journal, Computer Engineering, Computer Science journal, how to submit your paper, peer reviw journal, indexed journal, reserach and review articles, engineering journal, www.ijerd.com, research journals,
yahoo journals, bing journals, International Journal of Engineering Research and Development, google journals, hard copy of journal
International Journal of Engineering Research and Development (IJERD)IJERD Editor
journal publishing, how to publish research paper, Call For research paper, international journal, publishing a paper, IJERD, journal of science and technology, how to get a research paper published, publishing a paper, publishing of journal, publishing of research paper, reserach and review articles, IJERD Journal, How to publish your research paper, publish research paper, open access engineering journal, Engineering journal, Mathemetics journal, Physics journal, Chemistry journal, Computer Engineering, Computer Science journal, how to submit your paper, peer reviw journal, indexed journal, reserach and review articles, engineering journal, www.ijerd.com, research journals,
yahoo journals, bing journals, International Journal of Engineering Research and Development, google journals, hard copy of journal
Welcome to International Journal of Engineering Research and Development (IJERD)IJERD Editor
journal publishing, how to publish research paper, Call For research paper, international journal, publishing a paper, IJERD, journal of science and technology, how to get a research paper published, publishing a paper, publishing of journal, publishing of research paper, reserach and review articles, IJERD Journal, How to publish your research paper, publish research paper, open access engineering journal, Engineering journal, Mathemetics journal, Physics journal, Chemistry journal, Computer Engineering, Computer Science journal, how to submit your paper, peer reviw journal, indexed journal, reserach and review articles, engineering journal, www.ijerd.com, research journals,
yahoo journals, bing journals, International Journal of Engineering Research and Development, google journals, hard copy of journal
International Journal of Engineering Research and Development (IJERD)IJERD Editor
journal publishing, how to publish research paper, Call For research paper, international journal, publishing a paper, IJERD, journal of science and technology, how to get a research paper published, publishing a paper, publishing of journal, publishing of research paper, reserach and review articles, IJERD Journal, How to publish your research paper, publish research paper, open access engineering journal, Engineering journal, Mathemetics journal, Physics journal, Chemistry journal, Computer Engineering, Computer Science journal, how to submit your paper, peer reviw journal, indexed journal, reserach and review articles, engineering journal, www.ijerd.com, research journals,
yahoo journals, bing journals, International Journal of Engineering Research and Development, google journals, hard copy of journal
Welcome to International Journal of Engineering Research and Development (IJERD)IJERD Editor
journal publishing, how to publish research paper, Call For research paper, international journal, publishing a paper, IJERD, journal of science and technology, how to get a research paper published, publishing a paper, publishing of journal, publishing of research paper, reserach and review articles, IJERD Journal, How to publish your research paper, publish research paper, open access engineering journal, Engineering journal, Mathemetics journal, Physics journal, Chemistry journal, Computer Engineering, Computer Science journal, how to submit your paper, peer reviw journal, indexed journal, reserach and review articles, engineering journal, www.ijerd.com, research journals,
yahoo journals, bing journals, International Journal of Engineering Research and Development, google journals, hard copy of journal
Welcome to International Journal of Engineering Research and Development (IJERD)IJERD Editor
journal publishing, how to publish research paper, Call For research paper, international journal, publishing a paper, IJERD, journal of science and technology, how to get a research paper published, publishing a paper, publishing of journal, publishing of research paper, reserach and review articles, IJERD Journal, How to publish your research paper, publish research paper, open access engineering journal, Engineering journal, Mathemetics journal, Physics journal, Chemistry journal, Computer Engineering, Computer Science journal, how to submit your paper, peer reviw journal, indexed journal, reserach and review articles, engineering journal, www.ijerd.com, research journals,
yahoo journals, bing journals, International Journal of Engineering Research and Development, google journals, hard copy of journal
International Journal of Engineering Research and Development (IJERD)IJERD Editor
journal publishing, how to publish research paper, Call For research paper, international journal, publishing a paper, IJERD, journal of science and technology, how to get a research paper published, publishing a paper, publishing of journal, publishing of research paper, reserach and review articles, IJERD Journal, How to publish your research paper, publish research paper, open access engineering journal, Engineering journal, Mathemetics journal, Physics journal, Chemistry journal, Computer Engineering, Computer Science journal, how to submit your paper, peer reviw journal, indexed journal, reserach and review articles, engineering journal, www.ijerd.com, research journals,
yahoo journals, bing journals, International Journal of Engineering Research and Development, google journals, hard copy of journal
Simulation and Analysis of III V Characteristic and Bandgap Design for Hetero...ijtsrd
This research is the analysis of computer based simulation design for the semiconductor laser diode. The paper is emphasized by analyzing the band structure and voltage current characteristics of AlGaAs GaAs for the laser diode. In this paper, bandgap variation temperature dependence, voltage current V I , band diagram of the p n junction for laser diode are discussed briefly. On the other hand, this paper is emphasized band structure design and voltage current calculation using the mathematical model. The AlGaAs GaAs device technology is used for high speed optical communication. Thu Rein Ye Yint Win | Tin Tin Hla "Simulation and Analysis of III-V Characteristic and Bandgap Design for Heterojunction Laser Diode" Published in International Journal of Trend in Scientific Research and Development (ijtsrd), ISSN: 2456-6470, Volume-3 | Issue-5 , August 2019, URL: https://www.ijtsrd.com/papers/ijtsrd26542.pdfPaper URL: https://www.ijtsrd.com/engineering/electronics-and-communication-engineering/26542/simulation-and-analysis-of-iii-v-characteristic-and-bandgap-design-for-heterojunction-laser-diode/thu-rein-ye-yint-win
International Journal of Engineering Research and Applications (IJERA) is an open access online peer reviewed international journal that publishes research and review articles in the fields of Computer Science, Neural Networks, Electrical Engineering, Software Engineering, Information Technology, Mechanical Engineering, Chemical Engineering, Plastic Engineering, Food Technology, Textile Engineering, Nano Technology & science, Power Electronics, Electronics & Communication Engineering, Computational mathematics, Image processing, Civil Engineering, Structural Engineering, Environmental Engineering, VLSI Testing & Low Power VLSI Design etc.
Analytic Estimation of Two-Dimensional Electron Gas Density and Current-Volta...IJECEIAES
This paper is mainly dedicated to understand the phenomena governing the formation of two-dimensional electron gas (2DEG) confined in the quantum well which hold the role of the channel in the high electron density transistors (HEMT) based on AlGaN / GaN heterojunction. The theory takes into account: the crystal structure, the spontaneous and piezoelectric polarization concept, the formation mechanism of two-dimensional electron gas at the AlGaN / GaN interface, the approximate resolution of the Poisson and Schrödinger equations to determine the density of Two-dimensional electron gas after the analytical formula of the current-voltage characteristic is established. Our study is also concerned with the dependence of the twodimensional electron gas density on the following technological parameters: Aluminum molare fraction, AlGaN layer thickness and AlGaN layer doping, In order to control the influence of these parameters on the device performance. Finally, the current-voltage characteristic which reflects the variation of the drain-source current as a function of the modulation of the gate voltage has been discussed.
Plasmon Enhanced Internal Quantum Efficiency of CdSe/ZnS Quantum Dotsijrap
The effects of surface plasmon oscillations on the radiative recombination rate and internal quantum efficiency of silver coated CdSe/ZnS quantum dots imbedded in quartz matrix is studied theoretically and
numerically. The analysis is carried out by introducing the local field enhancement factor for the description of the dielectric function of the quantum dots together with the modified Drude model for the metal-coat that takes into account the effects of interband transitions and the size dependent damping
parameter. It is found out that the internal quantum efficiency of photoluminescence emission of the metalcoated CdSe/ZnS quantum dots is enhanced by about 5-folds compared with the quantum dots without metal-coat. Moreover, increasing the metal fraction of the coated CdSe/ZnS quantum dots from 0.80 to 0.92 results in a significant increase of the intensity that is accompanied by a blue-shift of the quantum efficiency curves. The results obtained can be utilized in the design and fabrication of optoelectronic devices that require high intensity of photoluminescence emission.
Efficiency Improvement of p-i-n Structure over p-n Structure and Effect of p-...iosrjce
IOSR Journal of Applied Physics (IOSR-JAP) is a double blind peer reviewed International Journal that provides rapid publication (within a month) of articles in all areas of physics and its applications. The journal welcomes publications of high quality papers on theoretical developments and practical applications in applied physics. Original research papers, state-of-the-art reviews, and high quality technical notes are invited for publications.
Electronic bands structure and gap in mid-infrared detector InAs/GaSb type II...IJERA Editor
We present here theoretical study of the electronic bands structure E (d1) of InAs (d1=25 Å)/GaSb (d2=25 Å) type
II superlattice at 4.2 K performed in the envelope function formalism. We study the effect of d1 and the offset ,
between heavy holes bands edges of InAs and GaSb, on the band gap Eg (), at the center of the first Brillouin
zone, and the semiconductor-to-semimetal transition. Eg (, T) decreases from 288.7 meV at 4.2 K to 230 meV
at 300K. In the investigated temperature range, the cut-off wavelength 4.3 m ≤ c ≤ 5.4 m situates this sample
as mid-wavelength infrared detector (MWIR). Our results are in good agreement with the experimental data
realized by C. Cervera et al.
ANALYSIS OF SMALL-SIGNAL PARAMETERS OF 2-D MODFET WITH POLARIZATION EFFECTS F...VLSICS Design
An improved analytical two dimensional (2-D) model for AlGaN/GaN modulation doped field effect
transistor (MODFET) has been developed. The model is based on the solution of 2-D Poisson’s equation.
The model includes the spontaneous and piezoelectric polarization effects. The effects of field dependent
mobility, velocity saturation and parasitic resistances are included in the current voltage characteristics of
the developed two dimensional electron gas (2-DEG) model. The small-signal microwave parameters have
been evaluated to determine the output characteristics, device transconductance and cut-off frequency for
50 nm gate length. The peak transconductance of 165mS/mm and a cut-off frequency of 120 GHz have been
obtained. The results so obtained are in close agreement with experimental data, thereby proving the
validity of the model.
ANALYSIS OF SMALL-SIGNAL PARAMETERS OF 2-D MODFET WITH POLARIZATION EFFECTS F...VLSICS Design
An improved analytical two dimensional (2-D) model for AlGaN/GaN modulation doped field effect transistor (MODFET) has been developed. The model is based on the solution of 2-D Poisson’s equation. The model includes the spontaneous and piezoelectric polarization effects. The effects of field dependent mobility, velocity saturation and parasitic resistances are included in the current voltage characteristics of the developed two dimensional electron gas (2-DEG) model. The small-signal microwave parameters have been evaluated to determine the output characteristics, device transconductance and cut-off frequency for 50 nm gate length. The peak transconductance of 165mS/mm and a cut-off frequency of 120 GHz have been obtained. The results so obtained are in close agreement with experimental data, thereby proving the validity of the model.
International Journal of Engineering Research and Applications (IJERA) is an open access online peer reviewed international journal that publishes research and review articles in the fields of Computer Science, Neural Networks, Electrical Engineering, Software Engineering, Information Technology, Mechanical Engineering, Chemical Engineering, Plastic Engineering, Food Technology, Textile Engineering, Nano Technology & science, Power Electronics, Electronics & Communication Engineering, Computational mathematics, Image processing, Civil Engineering, Structural Engineering, Environmental Engineering, VLSI Testing & Low Power VLSI Design etc.
International Journal of Engineering Research and Applications (IJERA) is a team of researchers not publication services or private publications running the journals for monetary benefits, we are association of scientists and academia who focus only on supporting authors who want to publish their work. The articles published in our journal can be accessed online, all the articles will be archived for real time access.
Our journal system primarily aims to bring out the research talent and the works done by sciaentists, academia, engineers, practitioners, scholars, post graduate students of engineering and science. This journal aims to cover the scientific research in a broader sense and not publishing a niche area of research facilitating researchers from various verticals to publish their papers. It is also aimed to provide a platform for the researchers to publish in a shorter of time, enabling them to continue further All articles published are freely available to scientific researchers in the Government agencies,educators and the general public. We are taking serious efforts to promote our journal across the globe in various ways, we are sure that our journal will act as a scientific platform for all researchers to publish their works online.
Enhancing the Performance of P3HT/Cdse Solar Cells by Optimal Designing of Ac...IOSRJEEE
The present study examined the influence of different condition like as doping , in active layer, on the performance of P3HT/CdSe Solar cells .In this work, we analyzed the best doping for the configuration of P3HT/ CdSe in order to improve the performance of the solar cell. For this aim, we investigated the current density of electrons, the electric field, the short-circuit current and the open-circuit voltage in different doping . The results indicate that when the doping is increased in P3Ht and is decreased in CdSe, the current density of electrons, the electric field, the short-circuit current, and the open-circuit voltage are increased. Finally, we obtained doping of and for electron and hole donor respectively as the best doping for this configuration
International Journal of Engineering Research and Applications (IJERA) is an open access online peer reviewed international journal that publishes research and review articles in the fields of Computer Science, Neural Networks, Electrical Engineering, Software Engineering, Information Technology, Mechanical Engineering, Chemical Engineering, Plastic Engineering, Food Technology, Textile Engineering, Nano Technology & science, Power Electronics, Electronics & Communication Engineering, Computational mathematics, Image processing, Civil Engineering, Structural Engineering, Environmental Engineering, VLSI Testing & Low Power VLSI Design etc.
Relationship between Refractive Index, Electronic Polarizavility, Optical Ene...ijceronline
Refractive index(n), Electronic Polarizability (αp), Optical Energy Gap(Eg) and optical electronegativity(Δχ* ), of I-III-VI2 and II-IV-V2 groups of ternary semiconductors have been calculated using Plasmon energy data on the basis best fit data, new relations have been proposed for the calculation of refractive index , electronic polarizability, optical energy gap and optical electronegativity. The calculated values of n, αp, Eg and (Δχ* ) from the new relations have been compared with the values reported by different researcher. An excellent agreement with calculated values and experimental values has been obtained.
A Novel Method for Prevention of Bandwidth Distributed Denial of Service AttacksIJERD Editor
Distributed Denial of Service (DDoS) Attacks became a massive threat to the Internet. Traditional
Architecture of internet is vulnerable to the attacks like DDoS. Attacker primarily acquire his army of Zombies,
then that army will be instructed by the Attacker that when to start an attack and on whom the attack should be
done. In this paper, different techniques which are used to perform DDoS Attacks, Tools that were used to
perform Attacks and Countermeasures in order to detect the attackers and eliminate the Bandwidth Distributed
Denial of Service attacks (B-DDoS) are reviewed. DDoS Attacks were done by using various Flooding
techniques which are used in DDoS attack.
The main purpose of this paper is to design an architecture which can reduce the Bandwidth
Distributed Denial of service Attack and make the victim site or server available for the normal users by
eliminating the zombie machines. Our Primary focus of this paper is to dispute how normal machines are
turning into zombies (Bots), how attack is been initiated, DDoS attack procedure and how an organization can
save their server from being a DDoS victim. In order to present this we implemented a simulated environment
with Cisco switches, Routers, Firewall, some virtual machines and some Attack tools to display a real DDoS
attack. By using Time scheduling, Resource Limiting, System log, Access Control List and some Modular
policy Framework we stopped the attack and identified the Attacker (Bot) machines
Hearing loss is one of the most common human impairments. It is estimated that by year 2015 more
than 700 million people will suffer mild deafness. Most can be helped by hearing aid devices depending on the
severity of their hearing loss. This paper describes the implementation and characterization details of a dual
channel transmitter front end (TFE) for digital hearing aid (DHA) applications that use novel micro
electromechanical- systems (MEMS) audio transducers and ultra-low power-scalable analog-to-digital
converters (ADCs), which enable a very-low form factor, energy-efficient implementation for next-generation
DHA. The contribution of the design is the implementation of the dual channel MEMS microphones and powerscalable
ADC system.
Influence of tensile behaviour of slab on the structural Behaviour of shear c...IJERD Editor
-A composite beam is composed of a steel beam and a slab connected by means of shear connectors
like studs installed on the top flange of the steel beam to form a structure behaving monolithically. This study
analyzes the effects of the tensile behavior of the slab on the structural behavior of the shear connection like slip
stiffness and maximum shear force in composite beams subjected to hogging moment. The results show that the
shear studs located in the crack-concentration zones due to large hogging moments sustain significantly smaller
shear force and slip stiffness than the other zones. Moreover, the reduction of the slip stiffness in the shear
connection appears also to be closely related to the change in the tensile strain of rebar according to the increase
of the load. Further experimental and analytical studies shall be conducted considering variables such as the
reinforcement ratio and the arrangement of shear connectors to achieve efficient design of the shear connection
in composite beams subjected to hogging moment.
Gold prospecting using Remote Sensing ‘A case study of Sudan’IJERD Editor
Gold has been extracted from northeast Africa for more than 5000 years, and this may be the first
place where the metal was extracted. The Arabian-Nubian Shield (ANS) is an exposure of Precambrian
crystalline rocks on the flanks of the Red Sea. The crystalline rocks are mostly Neoproterozoic in age. ANS
includes the nations of Israel, Jordan. Egypt, Saudi Arabia, Sudan, Eritrea, Ethiopia, Yemen, and Somalia.
Arabian Nubian Shield Consists of juvenile continental crest that formed between 900 550 Ma, when intra
oceanic arc welded together along ophiolite decorated arc. Primary Au mineralization probably developed in
association with the growth of intra oceanic arc and evolution of back arc. Multiple episodes of deformation
have obscured the primary metallogenic setting, but at least some of the deposits preserve evidence that they
originate as sea floor massive sulphide deposits.
The Red Sea Hills Region is a vast span of rugged, harsh and inhospitable sector of the Earth with
inimical moon-like terrain, nevertheless since ancient times it is famed to be an abode of gold and was a major
source of wealth for the Pharaohs of ancient Egypt. The Pharaohs old workings have been periodically
rediscovered through time. Recent endeavours by the Geological Research Authority of Sudan led to the
discovery of a score of occurrences with gold and massive sulphide mineralizations. In the nineties of the
previous century the Geological Research Authority of Sudan (GRAS) in cooperation with BRGM utilized
satellite data of Landsat TM using spectral ratio technique to map possible mineralized zones in the Red Sea
Hills of Sudan. The outcome of the study mapped a gossan type gold mineralization. Band ratio technique was
applied to Arbaat area and a signature of alteration zone was detected. The alteration zones are commonly
associated with mineralization. The alteration zones are commonly associated with mineralization. A filed check
confirmed the existence of stock work of gold bearing quartz in the alteration zone. Another type of gold
mineralization that was discovered using remote sensing is the gold associated with metachert in the Atmur
Desert.
Reducing Corrosion Rate by Welding DesignIJERD Editor
The paper addresses the importance of welding design to prevent corrosion at steel. Welding is
used to join pipe, profiles at bridges, spindle, and a lot more part of engineering construction. The
problems happened associated with welding are common issues in these fields, especially corrosion.
Corrosion can be reduced with many methods, they are painting, controlling humidity, and also good
welding design. In the research, it can be found that reducing residual stress on the welding can be
solved in corrosion rate reduction problem.
Preheating on 500oC and 600oC give better condition to reduce corosion rate than condition after
preheating 400oC. For all welding groove type, material with 500oC and 600oC preheating after 14 days
corrosion test is 0,5%-0,69% lost. Material with 400oC preheating after 14 days corrosion test is 0,57%-0,76%
lost.
Welding groove also influence corrosion rate. X and V type welding groove give better condition to reduce
corrosion rate than use 1/2V and 1/2 X welding groove. After 14 days corrosion test, the samples with
X welding groove type is 0,5%-0,57% lost. The samples with V welding groove after 14 days corrosion test is
0,51%-0,59% lost. The samples with 1/2V and 1/2X welding groove after 14 days corrosion test is 0,58%-
0,71% lost.
Router 1X3 – RTL Design and VerificationIJERD Editor
Routing is the process of moving a packet of data from source to destination and enables messages
to pass from one computer to another and eventually reach the target machine. A router is a networking device
that forwards data packets between computer networks. It is connected to two or more data lines from different
networks (as opposed to a network switch, which connects data lines from one single network). This paper,
mainly emphasizes upon the study of router device, it‟s top level architecture, and how various sub-modules of
router i.e. Register, FIFO, FSM and Synchronizer are synthesized, and simulated and finally connected to its top
module.
Active Power Exchange in Distributed Power-Flow Controller (DPFC) At Third Ha...IJERD Editor
This paper presents a component within the flexible ac-transmission system (FACTS) family, called
distributed power-flow controller (DPFC). The DPFC is derived from the unified power-flow controller (UPFC)
with an eliminated common dc link. The DPFC has the same control capabilities as the UPFC, which comprise
the adjustment of the line impedance, the transmission angle, and the bus voltage. The active power exchange
between the shunt and series converters, which is through the common dc link in the UPFC, is now through the
transmission lines at the third-harmonic frequency. DPFC multiple small-size single-phase converters which
reduces the cost of equipment, no voltage isolation between phases, increases redundancy and there by
reliability increases. The principle and analysis of the DPFC are presented in this paper and the corresponding
simulation results that are carried out on a scaled prototype are also shown.
Mitigation of Voltage Sag/Swell with Fuzzy Control Reduced Rating DVRIJERD Editor
Power quality has been an issue that is becoming increasingly pivotal in industrial electricity
consumers point of view in recent times. Modern industries employ Sensitive power electronic equipments,
control devices and non-linear loads as part of automated processes to increase energy efficiency and
productivity. Voltage disturbances are the most common power quality problem due to this the use of a large
numbers of sophisticated and sensitive electronic equipment in industrial systems is increased. This paper
discusses the design and simulation of dynamic voltage restorer for improvement of power quality and
reduce the harmonics distortion of sensitive loads. Power quality problem is occurring at non-standard
voltage, current and frequency. Electronic devices are very sensitive loads. In power system voltage sag,
swell, flicker and harmonics are some of the problem to the sensitive load. The compensation capability
of a DVR depends primarily on the maximum voltage injection ability and the amount of stored
energy available within the restorer. This device is connected in series with the distribution feeder at
medium voltage. A fuzzy logic control is used to produce the gate pulses for control circuit of DVR and the
circuit is simulated by using MATLAB/SIMULINK software.
Study on the Fused Deposition Modelling In Additive ManufacturingIJERD Editor
Additive manufacturing process, also popularly known as 3-D printing, is a process where a product
is created in a succession of layers. It is based on a novel materials incremental manufacturing philosophy.
Unlike conventional manufacturing processes where material is removed from a given work price to derive the
final shape of a product, 3-D printing develops the product from scratch thus obviating the necessity to cut away
materials. This prevents wastage of raw materials. Commonly used raw materials for the process are ABS
plastic, PLA and nylon. Recently the use of gold, bronze and wood has also been implemented. The complexity
factor of this process is 0% as in any object of any shape and size can be manufactured.
Spyware triggering system by particular string valueIJERD Editor
This computer programme can be used for good and bad purpose in hacking or in any general
purpose. We can say it is next step for hacking techniques such as keylogger and spyware. Once in this system if
user or hacker store particular string as a input after that software continually compare typing activity of user
with that stored string and if it is match then launch spyware programme.
A Blind Steganalysis on JPEG Gray Level Image Based on Statistical Features a...IJERD Editor
This paper presents a blind steganalysis technique to effectively attack the JPEG steganographic
schemes i.e. Jsteg, F5, Outguess and DWT Based. The proposed method exploits the correlations between
block-DCTcoefficients from intra-block and inter-block relation and the statistical moments of characteristic
functions of the test image is selected as features. The features are extracted from the BDCT JPEG 2-array.
Support Vector Machine with cross-validation is implemented for the classification.The proposed scheme gives
improved outcome in attacking.
Secure Image Transmission for Cloud Storage System Using Hybrid SchemeIJERD Editor
- Data over the cloud is transferred or transmitted between servers and users. Privacy of that
data is very important as it belongs to personal information. If data get hacked by the hacker, can be
used to defame a person’s social data. Sometimes delay are held during data transmission. i.e. Mobile
communication, bandwidth is low. Hence compression algorithms are proposed for fast and efficient
transmission, encryption is used for security purposes and blurring is used by providing additional
layers of security. These algorithms are hybridized for having a robust and efficient security and
transmission over cloud storage system.
Application of Buckley-Leverett Equation in Modeling the Radius of Invasion i...IJERD Editor
A thorough review of existing literature indicates that the Buckley-Leverett equation only analyzes
waterflood practices directly without any adjustments on real reservoir scenarios. By doing so, quite a number
of errors are introduced into these analyses. Also, for most waterflood scenarios, a radial investigation is more
appropriate than a simplified linear system. This study investigates the adoption of the Buckley-Leverett
equation to estimate the radius invasion of the displacing fluid during waterflooding. The model is also adopted
for a Microbial flood and a comparative analysis is conducted for both waterflooding and microbial flooding.
Results shown from the analysis doesn’t only records a success in determining the radial distance of the leading
edge of water during the flooding process, but also gives a clearer understanding of the applicability of
microbes to enhance oil production through in-situ production of bio-products like bio surfactans, biogenic
gases, bio acids etc.
Gesture Gaming on the World Wide Web Using an Ordinary Web CameraIJERD Editor
- Gesture gaming is a method by which users having a laptop/pc/x-box play games using natural or
bodily gestures. This paper presents a way of playing free flash games on the internet using an ordinary webcam
with the help of open source technologies. Emphasis in human activity recognition is given on the pose
estimation and the consistency in the pose of the player. These are estimated with the help of an ordinary web
camera having different resolutions from VGA to 20mps. Our work involved giving a 10 second documentary to
the user on how to play a particular game using gestures and what are the various kinds of gestures that can be
performed in front of the system. The initial inputs of the RGB values for the gesture component is obtained by
instructing the user to place his component in a red box in about 10 seconds after the short documentary before
the game is finished. Later the system opens the concerned game on the internet on popular flash game sites like
miniclip, games arcade, GameStop etc and loads the game clicking at various places and brings the state to a
place where the user is to perform only gestures to start playing the game. At any point of time the user can call
off the game by hitting the esc key and the program will release all of the controls and return to the desktop. It
was noted that the results obtained using an ordinary webcam matched that of the Kinect and the users could
relive the gaming experience of the free flash games on the net. Therefore effective in game advertising could
also be achieved thus resulting in a disruptive growth to the advertising firms.
Hardware Analysis of Resonant Frequency Converter Using Isolated Circuits And...IJERD Editor
-LLC resonant frequency converter is basically a combo of series as well as parallel resonant ckt. For
LCC resonant converter it is associated with a disadvantage that, though it has two resonant frequencies, the
lower resonant frequency is in ZCS region[5]. For this application, we are not able to design the converter
working at this resonant frequency. LLC resonant converter existed for a very long time but because of
unknown characteristic of this converter it was used as a series resonant converter with basically a passive
(resistive) load. . Here, it was designed to operate in switching frequency higher than resonant frequency of the
series resonant tank of Lr and Cr converter acts very similar to Series Resonant Converter. The benefit of LLC
resonant converter is narrow switching frequency range with light load[6] . Basically, the control ckt plays a
very imp. role and hence 555 Timer used here provides a perfect square wave as the control ckt provides no
slew rate which makes the square wave really strong and impenetrable. The dead band circuit provides the
exclusive dead band in micro seconds so as to avoid the simultaneous firing of two pairs of IGBT’s where one
pair switches off and the other on for a slightest period of time. Hence, the isolator ckt here is associated with
each and every ckt used because it acts as a driver and an isolation to each of the IGBT is provided with one
exclusive transformer supply[3]. The IGBT’s are fired using the appropriate signal using the previous boards
and hence at last a high frequency rectifier ckt with a filtering capacitor is used to get an exact dc
waveform .The basic goal of this particular analysis is to observe the wave forms and characteristics of
converters with differently positioned passive elements in the form of tank circuits.
Simulated Analysis of Resonant Frequency Converter Using Different Tank Circu...IJERD Editor
LLC resonant frequency converter is basically a combo of series as well as parallel resonant ckt. For
LCC resonant converter it is associated with a disadvantage that, though it has two resonant frequencies, the
lower resonant frequency is in ZCS region [5]. For this application, we are not able to design the converter
working at this resonant frequency. LLC resonant converter existed for a very long time but because of
unknown characteristic of this converter it was used as a series resonant converter with basically a passive
(resistive) load. . Here, it was designed to operate in switching frequency higher than resonant frequency of the
series resonant tank of Lr and Cr converter acts very similar to Series Resonant Converter. The benefit of LLC
resonant converter is narrow switching frequency range with light load[6] . Basically, the control ckt plays a
very imp. role and hence 555 Timer used here provides a perfect square wave as the control ckt provides no
slew rate which makes the square wave really strong and impenetrable. The dead band circuit provides the
exclusive dead band in micro seconds so as to avoid the simultaneous firing of two pairs of IGBT’s where one
pair switches off and the other on for a slightest period of time. Hence, the isolator ckt here is associated with
each and every ckt used because it acts as a driver and an isolation to each of the IGBT is provided with one
exclusive transformer supply[3]. The IGBT’s are fired using the appropriate signal using the previous boards
and hence at last a high frequency rectifier ckt with a filtering capacitor is used to get an exact dc
waveform .The basic goal of this particular analysis is to observe the wave forms and characteristics of
converters with differently positioned passive elements in the form of tank circuits. The supported simulation
is done through PSIM 6.0 software tool
Amateurs Radio operator, also known as HAM communicates with other HAMs through Radio
waves. Wireless communication in which Moon is used as natural satellite is called Moon-bounce or EME
(Earth -Moon-Earth) technique. Long distance communication (DXing) using Very High Frequency (VHF)
operated amateur HAM radio was difficult. Even with the modest setup having good transceiver, power
amplifier and high gain antenna with high directivity, VHF DXing is possible. Generally 2X11 YAGI antenna
along with rotor to set horizontal and vertical angle is used. Moon tracking software gives exact location,
visibility of Moon at both the stations and other vital data to acquire real time position of moon.
“MS-Extractor: An Innovative Approach to Extract Microsatellites on „Y‟ Chrom...IJERD Editor
Simple Sequence Repeats (SSR), also known as Microsatellites, have been extensively used as
molecular markers due to their abundance and high degree of polymorphism. The nucleotide sequences of
polymorphic forms of the same gene should be 99.9% identical. So, Microsatellites extraction from the Gene is
crucial. However, Microsatellites repeat count is compared, if they differ largely, he has some disorder. The Y
chromosome likely contains 50 to 60 genes that provide instructions for making proteins. Because only males
have the Y chromosome, the genes on this chromosome tend to be involved in male sex determination and
development. Several Microsatellite Extractors exist and they fail to extract microsatellites on large data sets of
giga bytes and tera bytes in size. The proposed tool “MS-Extractor: An Innovative Approach to extract
Microsatellites on „Y‟ Chromosome” can extract both Perfect as well as Imperfect Microsatellites from large
data sets of human genome „Y‟. The proposed system uses string matching with sliding window approach to
locate Microsatellites and extracts them.
Importance of Measurements in Smart GridIJERD Editor
- The need to get reliable supply, independence from fossil fuels, and capability to provide clean
energy at a fixed and lower cost, the existing power grid structure is transforming into Smart Grid. The
development of a smart energy distribution grid is a current goal of many nations. A Smart Grid should have
new capabilities such as self-healing, high reliability, energy management, and real-time pricing. This new era
of smart future grid will lead to major changes in existing technologies at generation, transmission and
distribution levels. The incorporation of renewable energy resources and distribution generators in the existing
grid will increase the complexity, optimization problems and instability of the system. This will lead to a
paradigm shift in the instrumentation and control requirements for Smart Grids for high quality, stable and
reliable electricity supply of power. The monitoring of the grid system state and stability relies on the
availability of reliable measurement of data. In this paper the measurement areas that highlight new
measurement challenges, development of the Smart Meters and the critical parameters of electric energy to be
monitored for improving the reliability of power systems has been discussed.
Study of Macro level Properties of SCC using GGBS and Lime stone powderIJERD Editor
One of the major environmental concerns is the disposal of the waste materials and utilization of
industrial by products. Lime stone quarries will produce millions of tons waste dust powder every year. Having
considerable high degree of fineness in comparision to cement this material may be utilized as a partial
replacement to cement. For this purpose an experiment is conducted to investigate the possibility of using lime
stone powder in the production of SCC with combined use GGBS and how it affects the fresh and mechanical
properties of SCC. First SCC is made by replacing cement with GGBS in percentages like 10, 20, 30, 40, 50 and
by taking the optimum mix with GGBS lime stone powder is blended to mix in percentages like 5, 10, 15, 20 as
a partial replacement to cement. Test results shows that the SCC mix with combination of 30% GGBS and 15%
limestone powder gives maximum compressive strength and fresh properties are also in the limits prescribed by
the EFNARC.
Study of Macro level Properties of SCC using GGBS and Lime stone powder
Welcome to International Journal of Engineering Research and Development (IJERD)
1. International Journal of Engineering Research and Development
e-ISSN: 2278-067X, p-ISSN: 2278-800X, www.ijerd.com
Volume 6, Issue 4 (March 2013), PP. 20-25
Polarizability with an effect of an Electric field for a donor
in spherical GaAs QDs
S.R.Chitra
M.Sc., M.Phil., Pgdca.,[Ph.D]., Research Fellow at Anna University , Thiruchirappalli , Pattukkottai Campus ,
Tanjore District , Tamil Nadu in India
Abstract:- In this present work, first I simplified and calculated the binding energy of a donor in
spherical quantum dots (QDs) by using a variational approach within the effective mass
approximation and computed for GaAs QD as a function of the dot size for different impurity
positions. Next I found out the expectation value of the Hamiltonion and also the binding energies
were computed for different values of the electric fields. I found that the value of the polarizability
obtained is several orders higher than the hydrogen atom value. My results are in good agreement with
previous theoretical findings.
Keywords:- Spherical quantum dot, Donor binding energy, Impurity state, Parabolic confinement
Quantum dots , quantum wells gallium arsenide, III-V semiconductors, impurity states, effective mass,
donor Binding , Semiconductor compounds, Polarizability of atoms, Polarizability of molecules.
PACS, 73.20.Dx , 73.20.Hb ,73.21.La , 73.21.-b , 73.61.Ey , 73.20.Hb , 71.18.+y, 71.38.+I , 71.20.Nr,
32.10.Dk, 33.15.Kr
I. INTRODUCTION
Recently, the evolution of the growth techniques such as molecular beam epitaxy and metal-organic
chemical vapor deposition combined with the use of the modulation-doped technique made it possible the
fabrication of low-dimensional heterostructures such as single and multiple quantum wells, quantum wires, and
quantum dots. In these systems, the restriction on the motion of the charge carriers allows us to control the
physical properties of the structures. The studies on these systems offer a wide range of potential applications in
the development of semiconductor optoelectronic devices [19-23].
GaInNAs/GaAs quantum well (QW) lasers have been attracting significant scientific interest mainly
due to their applications in 1.3- or 1.55-μm optical fiber communication [24-30]. These lasers are predominantly
based on GaInAsP alloys on the InP substrates, which have a higher temperature sensitivity compared to shorter
wavelength lasers that are grown on GaAs substrates. The high-temperature sensitivity is primarily due to Auger
recombination and the weak electron confinement resulting from the small conduction band offset in the
GaInAsP/InP material system.
GaInNAs alloys grown on GaAs substrates have been proposed as a possible alternative to the
GaInAsP/InP system for achieving lasers with high-temperature performance [31]. The deeper conduction band
well and the larger electron effective mass will provide better confinement for electrons and better match of the
valence and conduction band densities of state, which leads to a higher characteristic temperature and higher
operating temperature, higher efficiency, and higher output power [24-30].
The purpose of this work is to investigate the effect of an applied electric field on the binding energies
of shallow donor impurities GaAs QDs. The dimensions and the geometry of the system that we have used in
our work can be considered quite realistic due to the continuous development of the nm-structuring processes
(see,for example, Schweizer et al. [14]).
The results for the binding energy and polarizability in the effective-mass approximation,using a
variational scheme given and also given the values of the polarizability with an effect of an electric field for a
shallow hydrogenic donor in spherical GaAs QDs.
My results are in good agreement with previous theoretical findings.
The paper is organized as follows: in the ‘Theoretical overview’ section, the essential theoretical
background is described.
The next important section is the ‘Introduction about Polarizability’ section, and finally, my
calculations are given and ‘Conclusions’ section.
This work gives very important information about the binding energy and polarizability that can be
taken into account in experimental work related to absorption processes,and carrier dynamics, associated with
impurities in these heterostructures.
20
2. Polarizability with an effect of an Electric field for a donor in spherical GaAs QDs
The Hamiltonian of a single hydrogenic impurity in a spherical QD with parabolic confinement in the
effective mass approximation [2] can be written as
H= [P2/2m*] +1/2 [m*2r2] – e2 / |(r-ri)|
Where e and m* are, respectively, the electronic charge and effective mass, P is a momentum, is a
characteristic frequency, is the dielectric constant of the dot material, and ri gives the location of the impurity
with respect to the center of the dot.
In order to calculate the ground state of the impurity binding energy, the variational technique is
used[3], and for this the trial wave function is taken as
(r) = N() exp(-r2 /2 ) exp(-|(r-ri)|) ,
Where =m* /h /2. Here h being the Planck’s constant. is the variational parameter and N() is the
normalization constant. The ground state energy of the hydrogenic impurity is worked out from the above
equations by using the below relation.
E(,,ri) = <* /H/ > / <* />
Here * means the conjugate of the eigen function .
II. THEORY
We first derived the binding energy for two cases:
ri = 0 ., ie., the location of the impurity is zero.
ri = a .r., ie., impurity at the inner surface of the dot.
In case I, at ri = 0, the location of the impurity is zero.
Therefore the Hamiltonian of a single hydrogenic impurity in a spherical QD with parabolic confinement can be
written as
H= [P2/2m] +1/2 [m*2r2] – e2 / |(r-ri)|
The trial wave function is taken as
(r) = N() exp(-r2 /2 ) exp(-|(r-ri)|) ,
Where =m* /h /2. Here h being the Planck’s constant. is the variational parameter and N() is the
normalization constant.
Normalization condition: <* /> = 1
By equating everything, we get
(r) [1/2 m*2r2] (r) d = 2N2 e2 e/ / m* [(sqrt()) / 3/2 – 1/2]
This is the final solution for case (i). Then the binding energy will be,
<E> = 2N2h2 e/ /m* {-5 (sqrt()) /2 ½} - ……
By using this the binding energy was computed for GaAs QD as a function of the dot size.
When -1/2 (nm) = 2, then <E> in Ryd* = 13.1. When -1/2 (nm) = 10, then <E> in Ryd*
= 3.0.
*1 Ryd = 5.3 meV for GaAs
In this the present works are compared with the values of the references . Finally a graph is drawn
between the impurity binding energy versus the dot size. As the size - , the energy should 1 Ryd.
21
3. Polarizability with an effect of an Electric field for a donor in spherical GaAs QDs
In Case II, at ri = a, the location of the impurity is at the inner surface of the dot.
Therefore the Hamiltonian of a single hydrogenic impurity in a spherical QD with parabolic
confinement can be written as
H= [P2/2m*] +1/2 [m*2r2] – e2 / |(r-a)|
The trial wave function is taken as
(r) = N() exp(-r2 /2 ) exp(-|(r-a)|) ,
Where =m* /h /2. Here h being the Planck’s constant. is the variational parameter and N() is the
normalization constant.
Normalization condition: <* /> = 1
By equating everything, we get
(r) [1/2 m*2r2] (r) d = 2N2 e2 e/ / m* [(sqrt()) / 3/2 – (2 / ) +(1/2) - …..]
This is the final solution for case (i). Then the binding energy will be,
<E> = 2N2h2 e/ /m* {25 (sqrt()) /8 ½} - ……
By using this the binding energy was computed for GaAs QD as a function of the dot size.
When -1/2 (nm) = 2, then <E> in Ryd* = 12.0. When -1/2 (nm) = 10, then <E> in Ryd* = 3.8.
*1 Ryd = 5.3 meV for Ga As
In this the present works are compared with the values of the references .
Finally a graph is drawn between the impurity binding energy versus the dot size. For the case r i = a.
Comparisons of the <E> values, it reveals that the binding energy is larger in the case where the
impurity is at the centre of the dot.
III. POLARIZABILITY WITH AN EFFECT OF AN ELECTRIC FIELD
Introduction
Neutral nonpolar species have spherically symmetric arrangements of electrons in their electron clouds.
When in the presence of an electric field, their electron clouds can be distorted (Figure). The ease of this
distortion is defined as the polarizability of the atom or molecule. The created distortion of the electron cloud
causes the originally nonpolar molecule or atom to acquire a dipole moment. This induced dipole moment is
related to the polarizability of the molecule or atom and the strength of the electric field by the following
equation:
μind = α’ E
Where E denotes the strength of the electric field and α’ is the polarizability constant with units of C m 2 V-1.
Figure: A neutral nonpolar species's electron cloud is distorted by A.) an Ion and B.) a polar molecule to induce
a dipole moment.
22
4. Polarizability with an effect of an Electric field for a donor in spherical GaAs QDs
With the electrons held tightly in place in these smaller atoms, these atoms are typically not easily
polarized by external electric fields.
In contrast, large atoms with many electrons, such as negative ions with excess electrons, are easily
polarized. These atoms typically have very diffuse electron clouds and large atomic radii that limit the
interaction of their external electrons and the nucleus.
Factors that Influence Polarizability
The relationship between polarizability and the factors of electron density, atomic radii, and molecular
orientation is as follows:
The greater the amount of electrons, the less control the nuclear charge has on charge distribution, and
thus the increased polarizability of the atom.
The greater the distance of electrons from nuclear charge, the less control the nuclear charge has on the
charge distribution, and thus the increased polarizability of the atom.
Molecular orientation with respect to an electric field can affect polarizibility (labeled Orientation-
dependent), except for molecules that are: tetrahedral, octahedral or icosahedral (labeled Orientation-
independent).
This factor is more important for unsaturated molecules that contain areas of electron dense regions, such as
2,4-hexadiene. Greatest polarizability in these molecules is achieved when the electric field is applied parallel to
the molecule rather than perpendicular to the molecule.
Polarizability with an effect of an Electric field for a shallow hydrogenic donor in spherical GaAs QDs
with parabolic confinement
The effect of an applied electric field on the binding energies of shallow donor impurities in
rectangular cross section GaAs quantum-well wires (QWW) was presented by Montes et al. [3],
considering an infinite confinement potential and using a variational scheme. Quantum-mechanical
calculations of the carrier densities,elect ron and hole quasi-Fermi-levels,and various radiative decay times in
rectangular transversal-section GaAs QWWs have been performed under steady-state cw-laser excitation
conditions [13].
They considered the effects of the cw-laser intensity,the temperature,the physical dimensions of the structure,an
d a homogeneous distribution of electron-traps in the system.
The theoretical results for the laser-intensity-dependent quasi- Fermi-levels were found to be in
qualitative agreement with available experimental data [14]. However,the numerical data show that further
experimental and theoretical work is necessary.
In addition,there have been several reports on the polarizabilities of shallow-donor impurities in QWs and in
surface QWWs [15-18].
The presence of an external electric field in rectangular cross section QWWs modifies the impurity
band due to the fact that the field breaks the energy degeneracy for symmetrical impurity positions along the
transversal section of the wires. This is reflected by additional peaks in the impurity DOIS and in the absorption
and photoluminescence spectra.
I studied above theories and done the calculation for the polarizability with an effect of an electric field
for a shallow hydrogenic donor in spherical GaAs QDs with parabolic confinement, following variational
procedure within the effective mass approximations.
The computed result shows that the binding energy increases as the dot size decreases.
In the present work I investigate the effect of an applied electric field on the binding energies of
shallow donor impurities GaAs QDs. The dimensions and the geometry of the system that we have used in our
work can be considered quite realistic due to the continuous development of the nm-structuring processes
(see,for example, Schweizer et al. [14]).
I present the results for the binding energy and polarizability in the effective-mass approximation,using
a variational scheme for the infinite-confinement potential model and yield the values of the polarizability with
an effect of an electric field for a shallow hydrogenic donor in spherical GaAs QDs.
The donor atom in our system in an external electric field is given by,
H= [P2/2m] +1/2 [m*2r2] – e2 / |(r-ri)| + ez
We use the trial wave function, (r) = N() exp(-r2 /2 ) exp(-|(r-a)|) (1+ez)
where z = rcos. And is treated as a variational parameter.
In the case of ‘On- Centre ’ impurity (ri = 0), the normalization condition yields,
23
5. Polarizability with an effect of an Electric field for a donor in spherical GaAs QDs
N2 = 1 / 4 e/ [[sqrt()/3/2(…) –
/ [1+(22)/3] +( 2/ 5/2) (…) - …..]
If we put =0 , then we get the N2 value for case 1. (i.e., ri = 0)
I simplified this for second case also and I found out the expectation value of the Hamiltonion and also the
binding energies were computed for different values of the electric fields.
The results are presented in the below Table.
Graph
Using these datas, a graph was drawn for binding energy Vs 2, (see in figure).
The curve is linear. However for small values of , it is linear and gives the value of p as 0.7 * 102 *
-24
(10 cm3) for polarizability which is defined as
Table
<E> in Ryd*
-1/2 (nm)
=0 =10 =20 =40 =60
2 13.18 13.48 13.47 13.46 13.44
4 12.10 12.42 12.39 12.35 12.27
6 7.93 8.16 8.12 8.10 8.02
8 4.99 5.42 5.39 5.37 5.26
10 3.18 3.57 3.49 3.46 3.38
*1 Ryd = 5.3 meV for Ga As
p = [<E> / 2] | =>0= 0.7 * 102 * (10-24 cm3)
IV. CONCLUSION
We have presented a calculation for the polarizability with an effect of an Electric field for a shallow
hydrogenic donor in spherical GaAs QDs with parabolic confinement, following variational procedure within
the effective mass approximations. The computed result shows that the binding energy increases as the dot size
decreases. In spherical quantum dots, with an isotropic parabolic potential, the impurity binding energy is found
to decrease as the impurity moves away from the center, the effect being more pronounced for dots of smaller
sizes.
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