This document summarizes research on growing and characterizing patterned quantum well (QW) structures for full-color light emitting applications. Three different QWs emitting in the red, green, and yellow regions of the visible spectrum were integrated on a single indium phosphide substrate using sequential selective area epitaxy with a shadow mask. Micro-photoluminescence measurements showed well-defined excitonic emission peaks from each patterned region, demonstrating the feasibility of fabricating full-color light emitting diodes and lasers using this zinc cadmium magnesium selenide material system and growth technique.
Red–green–blue light emitting diodes and distributed Bragg reflectors based o...Oleg Maksimov
This document summarizes research on developing red, green, and blue light emitting diodes (LEDs) and distributed Bragg reflectors (DBRs) using ZnCdMgSe alloys lattice-matched to InP substrates. LED structures emitting across the visible spectrum were grown by varying quantum well thickness and composition. Lattice-matched DBRs with reflectivity peaks in red, green, and blue were also grown. Combining these LED and DBR structures could enable the design of high-performance visible LEDs and vertical cavity surface emitting lasers across the entire visible range using nearly identical material systems.
Formulation and evaluation of effect of different stabilizer at nanosuspensio...VIJAY SINGH
1. The study formulated and evaluated satranidazole nanosuspensions using different stabilizers to improve its solubility and dissolution rate.
2. Nanosuspensions were prepared using the nanoprecipitation technique and characterized for particle size, zeta potential, drug content, and in vitro drug release.
3. Results showed that formulations with poloxamer stabilizers had smaller particle sizes around 400 nm, high zeta potentials, and significantly improved drug release profiles compared to the pure drug. Formulation N1 with poloxamer 188 showed the best performance with a t50% of 15 hours.
1. The document discusses Rizal's time in Paris in 1889, including living arrangements, social activities, writings, and associations.
2. It notes Rizal's involvement with various intellectual societies focused on Philippine history and reform like the Propaganda Movement.
3. Key figures mentioned include Blumentritt, Pardo de Tavera, Juan Luna, and members of the Kidlat and Paisanos clubs.
Rizal wrote this letter to encourage 20 young women in Malolos who petitioned to open a night school for education. He pays homage to their desire to educate themselves, seeing it as a ray of hope in restoring the dignity of Filipino women. Rizal emphasizes the important role of Filipino mothers in teaching their children about God, country and community. He advises all women, whether mothers, daughters, wives or single, to protect their dignity through education while retaining their cultural values.
Rizal wrote two letters on June 20, 1892 that he left with his friend Dr. Lorenzo Marquez and instructed to be opened after his death. In the first letter to his family, Rizal expresses his love for them but says he must fulfill his duty to expose himself to danger and finish his work for the Philippines, even if it means death. He wants his family to be happy and not suffer persecution on his account. The second letter to his countrymen explains that he cannot live knowing others suffer unjust persecution because of him, so he prefers to face death and free many innocents from this persecution. Rizal expresses his love for his country and willingness to die for his duties and convictions.
This document provides a summary of Jose Rizal's literary works, including novels, poems, essays, notes, speeches and other writings. It discusses the bibliographies that were used to compile the list of Rizal's works and arrange them chronologically and thematically. The list then describes over 100 of Rizal's individual literary works, providing details on format, publication information, content summaries and notes on each.
Jose Rizal started painting at a young age and was asked by the mayor to paint a religious banner. He wrote his first work, "Sa Aking mga Kababata" at age 8, expressing Filipino nationalism. His most famous works were the novels Noli Me Tangere and El Filibusterismo, which ignited the spirit of Filipinos to fight for freedom against Spanish rule. All of Rizal's works criticized the Spanish and Catholic Church, leading to his arrest and execution.
Red–green–blue light emitting diodes and distributed Bragg reflectors based o...Oleg Maksimov
This document summarizes research on developing red, green, and blue light emitting diodes (LEDs) and distributed Bragg reflectors (DBRs) using ZnCdMgSe alloys lattice-matched to InP substrates. LED structures emitting across the visible spectrum were grown by varying quantum well thickness and composition. Lattice-matched DBRs with reflectivity peaks in red, green, and blue were also grown. Combining these LED and DBR structures could enable the design of high-performance visible LEDs and vertical cavity surface emitting lasers across the entire visible range using nearly identical material systems.
Formulation and evaluation of effect of different stabilizer at nanosuspensio...VIJAY SINGH
1. The study formulated and evaluated satranidazole nanosuspensions using different stabilizers to improve its solubility and dissolution rate.
2. Nanosuspensions were prepared using the nanoprecipitation technique and characterized for particle size, zeta potential, drug content, and in vitro drug release.
3. Results showed that formulations with poloxamer stabilizers had smaller particle sizes around 400 nm, high zeta potentials, and significantly improved drug release profiles compared to the pure drug. Formulation N1 with poloxamer 188 showed the best performance with a t50% of 15 hours.
1. The document discusses Rizal's time in Paris in 1889, including living arrangements, social activities, writings, and associations.
2. It notes Rizal's involvement with various intellectual societies focused on Philippine history and reform like the Propaganda Movement.
3. Key figures mentioned include Blumentritt, Pardo de Tavera, Juan Luna, and members of the Kidlat and Paisanos clubs.
Rizal wrote this letter to encourage 20 young women in Malolos who petitioned to open a night school for education. He pays homage to their desire to educate themselves, seeing it as a ray of hope in restoring the dignity of Filipino women. Rizal emphasizes the important role of Filipino mothers in teaching their children about God, country and community. He advises all women, whether mothers, daughters, wives or single, to protect their dignity through education while retaining their cultural values.
Rizal wrote two letters on June 20, 1892 that he left with his friend Dr. Lorenzo Marquez and instructed to be opened after his death. In the first letter to his family, Rizal expresses his love for them but says he must fulfill his duty to expose himself to danger and finish his work for the Philippines, even if it means death. He wants his family to be happy and not suffer persecution on his account. The second letter to his countrymen explains that he cannot live knowing others suffer unjust persecution because of him, so he prefers to face death and free many innocents from this persecution. Rizal expresses his love for his country and willingness to die for his duties and convictions.
This document provides a summary of Jose Rizal's literary works, including novels, poems, essays, notes, speeches and other writings. It discusses the bibliographies that were used to compile the list of Rizal's works and arrange them chronologically and thematically. The list then describes over 100 of Rizal's individual literary works, providing details on format, publication information, content summaries and notes on each.
Jose Rizal started painting at a young age and was asked by the mayor to paint a religious banner. He wrote his first work, "Sa Aking mga Kababata" at age 8, expressing Filipino nationalism. His most famous works were the novels Noli Me Tangere and El Filibusterismo, which ignited the spirit of Filipinos to fight for freedom against Spanish rule. All of Rizal's works criticized the Spanish and Catholic Church, leading to his arrest and execution.
High reflectivity symmetrically strained ZnxCdyMg1ÀxÀySe-based distributed Br...Oleg Maksimov
This summary provides the key details from the document in 3 sentences:
The document describes the growth and characterization of distributed Bragg reflector (DBR) structures made of alternating ZnCdSe and ZnCdMgSe layers grown on InP substrates by molecular beam epitaxy. Undoped DBR structures with up to 24 periods achieved a maximum reflectivity of 99%, while a chlorine-doped 12-period DBR achieved 89% reflectivity. Structural characterization confirmed high crystalline quality and layer thicknesses close to the designed optical thickness of λ/4n, demonstrating the suitability of these materials for applications requiring highly reflective mirrors such as vertical cavity surface emitting lasers.
3 d single gaas co axial nanowire solar cell for nanopillar-array photovoltai...ijcsa
Nanopillar array photovoltaics give unique advantages over today’s planar thin films in the areas of
optical properties and carrier collection, arising from their 3D geometry. The choice of the material
system, however, is essential in order to gain the advantage of the large surface/interface area associated
with nanopillars. Therefore, a well known Si and GaAs material are used in the design and studied in this
nanowire application. This work calculates and analyses the performance of the coaxial GaAs nanowire
and compared with that of Si nanowire using a semi-classical method. The current-voltage characteristics
are investigated for both under dark and AM1.5G illumination. It is found that GaAs nanowire gives almost
double efficiency with its counterpart Si nanowire. Their TCAD simulations can be validated reasonably
with that of published experimental result.
Morphological and Optical Study of Sol-Gel SpinCoated Nanostructured CdSThin ...iosrjce
Nanostructured CdS thin films of different thicknesses were deposited on a cleaned glass substrate
using sol-gel spin coating technique. CdS thin films were prepared using cadmium acetate as cadmium source
and thiourea as sulfur source. The Morphological, chemical composition, and optical properties of the spin- coated
CdS thin film were studied using field emission- scanning electron microscopy (FE-SEM), Energy dispersive X –ray
(EDX) spectroscopy, and a UV-Vis-NIR spectrophotometer.The morphological results revealed that the films consist
of agglomerated spherical CdS nanoparticles with diameter < 20 nm, which distributed uniformly on the substrate
surface.The films show high transmittance > 90% and very strong absorption edge at 295 nm.The absorption edge
shifts towards longer wavelength as the film thickness increased.
1) The surface-emitting laser (SEL), also known as the vertical-cavity surface-emitting laser (VCSEL), was invented in 1977 and first demonstrated in 1979. It emits light from its surface rather than from its edge like conventional lasers.
2) VCSEL research has progressed through several generations, reaching commercial applications in the late 1980s and 1990s. Key milestones included room temperature operation in 1988, sub-milliamp threshold currents, and introduction into gigabit ethernet networks in 1999.
3) VCSELs have many advantages over conventional lasers including ultralow threshold currents (as low as microamps), high modulation bandwidth, easy testing and packaging, and potential
This document summarizes research on growing and characterizing thin films of beta-indium selenide (β-In2Se3) nanosheets. Key points:
- β-In2Se3 nanosheets with thicknesses ranging from 2.8 to 100 nm were grown on substrates like SiO2/Si, mica, and graphite using physical vapor transport.
- Raman spectroscopy, X-ray diffraction, and photoluminescence measurements confirmed the films were β-In2Se3 and exhibited a blue shift in the photoluminescence peak with decreasing thickness, indicating quantum confinement effects.
- The β-In2Se3 films showed high photorespons
This document summarizes research on growing and characterizing thin films of beta-indium selenide (β-In2Se3) nanosheets. Key points:
- β-In2Se3 nanosheets with thicknesses ranging from 2.8 to 100 nm were grown on substrates like SiO2/Si, mica, and graphite using physical vapor transport.
- Raman spectroscopy, X-ray diffraction, and photoluminescence measurements confirmed the films were β-In2Se3 and exhibited a blue shift in the photoluminescence peak with decreasing thickness, indicating quantum confinement effects.
- The β-In2Se3 films showed high photorespons
This document proposes a novel approach to selectively functionalize a specific face of gold nanorods synthesized using on-wire lithography (OWL). The nanorods have a multi-segmented gold-nickel-gold composition. The method uses a self-assembled monolayer to protect exposed gold surfaces, while etching removes the nickel segment and exposes a clean gold surface. This exposed gold surface can then be selectively functionalized, such as with biotinylated molecules and streptavidin-coated nanoparticles, demonstrating the approach. Experiments are described to determine the optimal nickel etchant concentration and time needed to remove the nickel without damaging the gold segments.
The document discusses computational screening of 2D materials for different applications. It describes research being conducted at Allama Iqbal Open University on using computational methods to predict properties of 2D materials and study their potential applications in areas like photocatalysis, gas sensing, and thermoelectric devices. The research group is computationally investigating various 2D materials like MoSi2N4, WGe2N4, and WSi2N4 to understand their structural stability, electronic properties, and suitability for applications. The introduction provides background on 2D materials and their unique properties compared to bulk materials.
This document summarizes research on photovoltaic structures using thermally evaporated tin sulfide thin films. Key points:
- Tin sulfide films were deposited by thermal evaporation onto glass substrates in thicknesses ranging from 100-300nm.
- The films exhibited n-type conductivity at low thicknesses, transitioning to p-type at higher thicknesses. Bandgaps ranged from 2.1-1.7eV.
- CdS/SnS photovoltaic cells showed open circuit voltages up to 400mV, short circuit current densities up to 0.061mA/cm2, and conversion efficiencies up to 1.49% under 106mW/cm2 illumination.
A Front Surface Optimization Study for Photovoltaic ApplicationTELKOMNIKA JOURNAL
This document summarizes a study on optimizing the front surface of silicon solar cells to reduce reflectance through antireflection coatings and surface texturing. Silicon nitride films were deposited using plasma-enhanced chemical vapor deposition and hot-wire chemical vapor deposition on silicon substrates, and showed weighted average reflectances of 1.5% and 1.8% respectively. Random pyramid surface textures were formed on silicon using potassium hydroxide etching for 30 minutes, achieving low reflectance. Combining the optimized silicon nitride coatings with the textured surfaces further reduced weighted average reflectances to 1.5% for PECVD and 1.8% for HWCVD coatings.
Design and analysis of multicolor qdip based on metallic nanoslits array modi...University of Technology
Design and Analysis of Multicolor QDIP Based
on Metallic Nanoslits Array
Alireza Mobini and Vahid Ahmadi, Senior Member, IEEE
its a view of their work.
An integrated approach to realizing high performance liquid-junction quantum ...Emerson Kohlrausch
This study demonstrates a liquid-junction quantum dot sensitized solar cell with certified power conversion efficiencies exceeding 5%, a record for this type of solar cell. The solar cells utilize low-cost, low-toxicity CuInSexS2−x quantum dots synthesized via solution processing. Surface treatment of the quantum dots with zinc or cadmium ions is shown to reduce surface trap states and increase open circuit voltage and short circuit current. Optimization of the methanol-based polysulfide electrolyte and use of a mesoporous cuprous sulfide cathode further improve performance by reducing series resistance. The resulting solar cells demonstrate high stability over several months under ambient conditions, offering potential for low-cost and robust photovoltaics.
This document discusses research into developing monolithically integrated cadmium telluride (CdTe) solar cell devices deposited via atmospheric pressure metal-organic chemical vapor deposition (AP-MOCVD). The research aims to improve the fabrication process and efficiency of CdTe modules. Key steps studied include AP-MOCVD deposition of CdZnS/CdTe layers, addition of back contacts via thermal evaporation or screen printing, monolithic integration via mechanical scribing, and characterization of solar cell performance. Issues addressed include delamination, improving scribing precision, and damage to scribing tips. The goal is to advance the process from single solar cells to interconnected photovoltaic modules.
Optical characterization of Se90S10-xCdx thin filmsIOSR Journals
This document summarizes research on the optical characterization of Se90S10-xCdx thin films with varying concentrations of cadmium (Cd). Thin films were deposited via thermal evaporation and their structural, optical, and electrical properties were analyzed using techniques such as X-ray diffraction, differential thermal analysis, and spectrophotometry. The addition of Cd was found to decrease the refractive index and absorption coefficient compared to films without Cd. Optical bandgap, dielectric constant, and other optical parameters were estimated from transmission measurements and used to interpret the effect of localized electronic states within the amorphous semiconductor films.
This document discusses advances in laser holographic lithography techniques for fabricating 3D nanostructures. It describes how holographic lithography can be achieved using a single optical element such as a diffractive phase mask or deflective prism. Specifically, it provides examples of using a 2D phase mask and a 4-sided prism to generate interference patterns that can produce diamond-like 3D photonic crystal structures in a single laser exposure, overcoming limitations of previous multi-element approaches. Controlling the phase of laser beams is shown to be crucial for enabling the fabrication of complex 3D structures using these single-element holographic lithography methods.
A weak lensing_mass_reconstruction_of _the_large_scale_filament_massive_galax...Sérgio Sacani
This study reports the first weak-lensing detection of a large-scale filament funneling matter onto the core of the massive galaxy cluster MACSJ0717.5+3745. The analysis is based on Hubble Space Telescope images covering an area of 10x20 arcmin^2 around the cluster. A weak-lensing mass reconstruction detects the filament within 3 sigma and measures its projected length as ~4.5 h^-1 Mpc and mean density as (2.92±0.66)×10^8 h74 M⊙ kpc^-2. Assuming constraints on the filament's geometry based on galaxy velocities, the three-dimensional length is estimated to be 18 h^-1 M
The document reviews epitaxial quantum dot solar cells. It discusses how quantum dots are fabricated using epitaxial growth and how they can be incorporated into intermediate band solar cells. While quantum dots enable additional infrared absorption to increase photocurrent, this gain is offset by a decrease in open circuit voltage. Various techniques have been explored to improve quantum dot solar cell efficiency, such as strain compensation during growth and optimizing dot placement and doping, but efficiency remains below conventional GaAs solar cells. The key challenge is overcoming the open circuit voltage reduction while maintaining photocurrent enhancement.
Performance Indicators For Grid-Connected PV Systems: A Case Study In Casabla...IOSRJEEE
The main goal of this paper is to compare a one year performance of 5.94 KWp grid-connected PV module technology systems, constituted by three types of photovoltaic solar panels (Monocrystalline (mc-Si) (2.04KWp), polycrystalline (pc-Si) (2.04KWp) and amorphous (a-Si) (1.86 KWp))-silicon installed on the roof of the faculty of science Ben M’sik Casablanca. The study is based on the data collected along 2 years (2015- 2016) about energy production. The elements of performance evaluated monthly and annually include: energy output, system efficiency, reference yield, final yield, performance ratio, annual capacity factor and CO2 emissions avoided. The investigation of the annual: productivity (EAC,Y), system efficiency (Ƞ푠푦푠 ,푌 ), performance ratio (PR), capacity factor (CF) and amount of CO2 emissions avoided for a-Si are found as 2941.15KWh, 7.21%, 73.1%, 18.05% and 1.765tonsrespectively. EAC,Y, Ƞ푠푦푠,푌 , PR, CF and amount of CO2 emissions avoided for pc-Si are found as 3331.15KWh, 11.4%, 75.6%, 18.64% and 1.999tons respectively. Mc-Si installation exhibits slightly higher values of EAC,Y, Ƞ푠푦푠 ,푌 , PR, CF and amount of CO2 emissions avoided which are 3370.89KWh, 11.7%, 76.7%, 18.86% and 2.023tons respectively. The results show that mc-Si system presents the best performance followed by pc-Si and by a-Si. In addition, a developed study was carried out to establish the relation between the efficiency and temperature, performance ratios and radiation, in order to know the behavior of each technology for each period of the year and for the whole year. Without forgetting a comparison of all results found with the previous studies in different locations.
1996 strain in nanoscale germanium hut clusters on si(001) studied by x ray d...pmloscholte
This document summarizes a study that used x-ray diffraction and scanning tunneling microscopy to investigate the strain in nanoscale germanium hut clusters on silicon substrates. The key findings are:
1) X-ray diffraction measurements revealed contributions from the hut clusters that allowed determining the strain distribution uniquely from the clusters.
2) The germanium clusters are almost fully strained with 0.5% misfit at the interface but strain is relaxed towards the apex, with 4.2% misfit indicating the natural germanium lattice spacing.
3) By modeling the asymmetric intensity distributions around diffraction peaks, the study determined that strain is relaxed uniformly through the hut clusters from a maximum near the interface to a minimum
Design modern structure for heterojunction quantum dot solar cells IJECEIAES
This paper proposal new structure for improving the optical, electrical characteristics and efficiency of 3 rd generation heterojunction quantum dot solar cell (HJQDSC) (ITO/CdS/QDPbS/Au) model by using the quantum dot window layer instead of bulk structure layers cell. Also, this paper presents theoretically analysis for the performance of the proposal HJQDSC (ITO/QDCdS/QDPbS/Au) structure. The new design structure was applied on traditional (SnO2/CdS/CdTe/Cu) and (ZnO/CdS/CIGS/Mo) thin film solar cells which based on sub-micro absorber layer thickness models by replacing the bulk CdTe, CIGS absorber layers and CdS window layer with quantum dot size materials to achieve higher efficiency with lesser usage layer material. Also, it has been studied the effect of using semiconductors layers in quantum dots size on electric and optical properties of thin film solar cells and the effect of window and absorber layers quantum dots radii on the performance of solar cells. Finally, a thermal efficiency analysis has been investigated for explaining the importance of new structure HJQD solar cells.
Giant LO oscillation in the Zn1yxBex(Se,Te) multi-phonons percolative alloysOleg Maksimov
This document discusses Raman scattering experiments on ZnBe(Se,Te) alloys. It finds that within the percolation regime of 0.19<x<0.81:
1) The low-frequency LO component is overdamped.
2) The high-frequency LO component exhibits a red asymmetry and apparent blue shift compared to predictions.
3) These anomalies can be explained by a discrete multi-mode description for the low- and high-frequency components, where coupling between modes via the macroscopic polarization field results in a transfer of oscillator strength building a "giant" LO oscillation.
Effect of nitridation on crystallinity of GaN grown on GaAs by MBEOleg Maksimov
1) GaN films were grown on GaAs substrates using plasma-assisted molecular beam epitaxy. The growth process involved substrate nitridation, deposition of a low-temperature buffer layer, and high-temperature film growth.
2) The effect of nitridation temperature on film crystallinity was studied using X-ray diffraction. Low-temperature (400°C) nitridation promoted the growth of c-oriented hexagonal α-GaN, while higher nitridation temperatures resulted in mis-oriented domains and inclusions of cubic β-GaN.
3) It was demonstrated that controlling the nitridation temperature is critical for achieving high quality GaN crystal growth, and nitridation must be performed at
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High reflectivity symmetrically strained ZnxCdyMg1ÀxÀySe-based distributed Br...Oleg Maksimov
This summary provides the key details from the document in 3 sentences:
The document describes the growth and characterization of distributed Bragg reflector (DBR) structures made of alternating ZnCdSe and ZnCdMgSe layers grown on InP substrates by molecular beam epitaxy. Undoped DBR structures with up to 24 periods achieved a maximum reflectivity of 99%, while a chlorine-doped 12-period DBR achieved 89% reflectivity. Structural characterization confirmed high crystalline quality and layer thicknesses close to the designed optical thickness of λ/4n, demonstrating the suitability of these materials for applications requiring highly reflective mirrors such as vertical cavity surface emitting lasers.
3 d single gaas co axial nanowire solar cell for nanopillar-array photovoltai...ijcsa
Nanopillar array photovoltaics give unique advantages over today’s planar thin films in the areas of
optical properties and carrier collection, arising from their 3D geometry. The choice of the material
system, however, is essential in order to gain the advantage of the large surface/interface area associated
with nanopillars. Therefore, a well known Si and GaAs material are used in the design and studied in this
nanowire application. This work calculates and analyses the performance of the coaxial GaAs nanowire
and compared with that of Si nanowire using a semi-classical method. The current-voltage characteristics
are investigated for both under dark and AM1.5G illumination. It is found that GaAs nanowire gives almost
double efficiency with its counterpart Si nanowire. Their TCAD simulations can be validated reasonably
with that of published experimental result.
Morphological and Optical Study of Sol-Gel SpinCoated Nanostructured CdSThin ...iosrjce
Nanostructured CdS thin films of different thicknesses were deposited on a cleaned glass substrate
using sol-gel spin coating technique. CdS thin films were prepared using cadmium acetate as cadmium source
and thiourea as sulfur source. The Morphological, chemical composition, and optical properties of the spin- coated
CdS thin film were studied using field emission- scanning electron microscopy (FE-SEM), Energy dispersive X –ray
(EDX) spectroscopy, and a UV-Vis-NIR spectrophotometer.The morphological results revealed that the films consist
of agglomerated spherical CdS nanoparticles with diameter < 20 nm, which distributed uniformly on the substrate
surface.The films show high transmittance > 90% and very strong absorption edge at 295 nm.The absorption edge
shifts towards longer wavelength as the film thickness increased.
1) The surface-emitting laser (SEL), also known as the vertical-cavity surface-emitting laser (VCSEL), was invented in 1977 and first demonstrated in 1979. It emits light from its surface rather than from its edge like conventional lasers.
2) VCSEL research has progressed through several generations, reaching commercial applications in the late 1980s and 1990s. Key milestones included room temperature operation in 1988, sub-milliamp threshold currents, and introduction into gigabit ethernet networks in 1999.
3) VCSELs have many advantages over conventional lasers including ultralow threshold currents (as low as microamps), high modulation bandwidth, easy testing and packaging, and potential
This document summarizes research on growing and characterizing thin films of beta-indium selenide (β-In2Se3) nanosheets. Key points:
- β-In2Se3 nanosheets with thicknesses ranging from 2.8 to 100 nm were grown on substrates like SiO2/Si, mica, and graphite using physical vapor transport.
- Raman spectroscopy, X-ray diffraction, and photoluminescence measurements confirmed the films were β-In2Se3 and exhibited a blue shift in the photoluminescence peak with decreasing thickness, indicating quantum confinement effects.
- The β-In2Se3 films showed high photorespons
This document summarizes research on growing and characterizing thin films of beta-indium selenide (β-In2Se3) nanosheets. Key points:
- β-In2Se3 nanosheets with thicknesses ranging from 2.8 to 100 nm were grown on substrates like SiO2/Si, mica, and graphite using physical vapor transport.
- Raman spectroscopy, X-ray diffraction, and photoluminescence measurements confirmed the films were β-In2Se3 and exhibited a blue shift in the photoluminescence peak with decreasing thickness, indicating quantum confinement effects.
- The β-In2Se3 films showed high photorespons
This document proposes a novel approach to selectively functionalize a specific face of gold nanorods synthesized using on-wire lithography (OWL). The nanorods have a multi-segmented gold-nickel-gold composition. The method uses a self-assembled monolayer to protect exposed gold surfaces, while etching removes the nickel segment and exposes a clean gold surface. This exposed gold surface can then be selectively functionalized, such as with biotinylated molecules and streptavidin-coated nanoparticles, demonstrating the approach. Experiments are described to determine the optimal nickel etchant concentration and time needed to remove the nickel without damaging the gold segments.
The document discusses computational screening of 2D materials for different applications. It describes research being conducted at Allama Iqbal Open University on using computational methods to predict properties of 2D materials and study their potential applications in areas like photocatalysis, gas sensing, and thermoelectric devices. The research group is computationally investigating various 2D materials like MoSi2N4, WGe2N4, and WSi2N4 to understand their structural stability, electronic properties, and suitability for applications. The introduction provides background on 2D materials and their unique properties compared to bulk materials.
This document summarizes research on photovoltaic structures using thermally evaporated tin sulfide thin films. Key points:
- Tin sulfide films were deposited by thermal evaporation onto glass substrates in thicknesses ranging from 100-300nm.
- The films exhibited n-type conductivity at low thicknesses, transitioning to p-type at higher thicknesses. Bandgaps ranged from 2.1-1.7eV.
- CdS/SnS photovoltaic cells showed open circuit voltages up to 400mV, short circuit current densities up to 0.061mA/cm2, and conversion efficiencies up to 1.49% under 106mW/cm2 illumination.
A Front Surface Optimization Study for Photovoltaic ApplicationTELKOMNIKA JOURNAL
This document summarizes a study on optimizing the front surface of silicon solar cells to reduce reflectance through antireflection coatings and surface texturing. Silicon nitride films were deposited using plasma-enhanced chemical vapor deposition and hot-wire chemical vapor deposition on silicon substrates, and showed weighted average reflectances of 1.5% and 1.8% respectively. Random pyramid surface textures were formed on silicon using potassium hydroxide etching for 30 minutes, achieving low reflectance. Combining the optimized silicon nitride coatings with the textured surfaces further reduced weighted average reflectances to 1.5% for PECVD and 1.8% for HWCVD coatings.
Design and analysis of multicolor qdip based on metallic nanoslits array modi...University of Technology
Design and Analysis of Multicolor QDIP Based
on Metallic Nanoslits Array
Alireza Mobini and Vahid Ahmadi, Senior Member, IEEE
its a view of their work.
An integrated approach to realizing high performance liquid-junction quantum ...Emerson Kohlrausch
This study demonstrates a liquid-junction quantum dot sensitized solar cell with certified power conversion efficiencies exceeding 5%, a record for this type of solar cell. The solar cells utilize low-cost, low-toxicity CuInSexS2−x quantum dots synthesized via solution processing. Surface treatment of the quantum dots with zinc or cadmium ions is shown to reduce surface trap states and increase open circuit voltage and short circuit current. Optimization of the methanol-based polysulfide electrolyte and use of a mesoporous cuprous sulfide cathode further improve performance by reducing series resistance. The resulting solar cells demonstrate high stability over several months under ambient conditions, offering potential for low-cost and robust photovoltaics.
This document discusses research into developing monolithically integrated cadmium telluride (CdTe) solar cell devices deposited via atmospheric pressure metal-organic chemical vapor deposition (AP-MOCVD). The research aims to improve the fabrication process and efficiency of CdTe modules. Key steps studied include AP-MOCVD deposition of CdZnS/CdTe layers, addition of back contacts via thermal evaporation or screen printing, monolithic integration via mechanical scribing, and characterization of solar cell performance. Issues addressed include delamination, improving scribing precision, and damage to scribing tips. The goal is to advance the process from single solar cells to interconnected photovoltaic modules.
Optical characterization of Se90S10-xCdx thin filmsIOSR Journals
This document summarizes research on the optical characterization of Se90S10-xCdx thin films with varying concentrations of cadmium (Cd). Thin films were deposited via thermal evaporation and their structural, optical, and electrical properties were analyzed using techniques such as X-ray diffraction, differential thermal analysis, and spectrophotometry. The addition of Cd was found to decrease the refractive index and absorption coefficient compared to films without Cd. Optical bandgap, dielectric constant, and other optical parameters were estimated from transmission measurements and used to interpret the effect of localized electronic states within the amorphous semiconductor films.
This document discusses advances in laser holographic lithography techniques for fabricating 3D nanostructures. It describes how holographic lithography can be achieved using a single optical element such as a diffractive phase mask or deflective prism. Specifically, it provides examples of using a 2D phase mask and a 4-sided prism to generate interference patterns that can produce diamond-like 3D photonic crystal structures in a single laser exposure, overcoming limitations of previous multi-element approaches. Controlling the phase of laser beams is shown to be crucial for enabling the fabrication of complex 3D structures using these single-element holographic lithography methods.
A weak lensing_mass_reconstruction_of _the_large_scale_filament_massive_galax...Sérgio Sacani
This study reports the first weak-lensing detection of a large-scale filament funneling matter onto the core of the massive galaxy cluster MACSJ0717.5+3745. The analysis is based on Hubble Space Telescope images covering an area of 10x20 arcmin^2 around the cluster. A weak-lensing mass reconstruction detects the filament within 3 sigma and measures its projected length as ~4.5 h^-1 Mpc and mean density as (2.92±0.66)×10^8 h74 M⊙ kpc^-2. Assuming constraints on the filament's geometry based on galaxy velocities, the three-dimensional length is estimated to be 18 h^-1 M
The document reviews epitaxial quantum dot solar cells. It discusses how quantum dots are fabricated using epitaxial growth and how they can be incorporated into intermediate band solar cells. While quantum dots enable additional infrared absorption to increase photocurrent, this gain is offset by a decrease in open circuit voltage. Various techniques have been explored to improve quantum dot solar cell efficiency, such as strain compensation during growth and optimizing dot placement and doping, but efficiency remains below conventional GaAs solar cells. The key challenge is overcoming the open circuit voltage reduction while maintaining photocurrent enhancement.
Performance Indicators For Grid-Connected PV Systems: A Case Study In Casabla...IOSRJEEE
The main goal of this paper is to compare a one year performance of 5.94 KWp grid-connected PV module technology systems, constituted by three types of photovoltaic solar panels (Monocrystalline (mc-Si) (2.04KWp), polycrystalline (pc-Si) (2.04KWp) and amorphous (a-Si) (1.86 KWp))-silicon installed on the roof of the faculty of science Ben M’sik Casablanca. The study is based on the data collected along 2 years (2015- 2016) about energy production. The elements of performance evaluated monthly and annually include: energy output, system efficiency, reference yield, final yield, performance ratio, annual capacity factor and CO2 emissions avoided. The investigation of the annual: productivity (EAC,Y), system efficiency (Ƞ푠푦푠 ,푌 ), performance ratio (PR), capacity factor (CF) and amount of CO2 emissions avoided for a-Si are found as 2941.15KWh, 7.21%, 73.1%, 18.05% and 1.765tonsrespectively. EAC,Y, Ƞ푠푦푠,푌 , PR, CF and amount of CO2 emissions avoided for pc-Si are found as 3331.15KWh, 11.4%, 75.6%, 18.64% and 1.999tons respectively. Mc-Si installation exhibits slightly higher values of EAC,Y, Ƞ푠푦푠 ,푌 , PR, CF and amount of CO2 emissions avoided which are 3370.89KWh, 11.7%, 76.7%, 18.86% and 2.023tons respectively. The results show that mc-Si system presents the best performance followed by pc-Si and by a-Si. In addition, a developed study was carried out to establish the relation between the efficiency and temperature, performance ratios and radiation, in order to know the behavior of each technology for each period of the year and for the whole year. Without forgetting a comparison of all results found with the previous studies in different locations.
1996 strain in nanoscale germanium hut clusters on si(001) studied by x ray d...pmloscholte
This document summarizes a study that used x-ray diffraction and scanning tunneling microscopy to investigate the strain in nanoscale germanium hut clusters on silicon substrates. The key findings are:
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2) The germanium clusters are almost fully strained with 0.5% misfit at the interface but strain is relaxed towards the apex, with 4.2% misfit indicating the natural germanium lattice spacing.
3) By modeling the asymmetric intensity distributions around diffraction peaks, the study determined that strain is relaxed uniformly through the hut clusters from a maximum near the interface to a minimum
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Similar to Patterned three-color ZnCdSe/ZnCdMgSe quantum-well structures for integrated full-color and white light emitters (20)
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This document discusses Raman scattering experiments on ZnBe(Se,Te) alloys. It finds that within the percolation regime of 0.19<x<0.81:
1) The low-frequency LO component is overdamped.
2) The high-frequency LO component exhibits a red asymmetry and apparent blue shift compared to predictions.
3) These anomalies can be explained by a discrete multi-mode description for the low- and high-frequency components, where coupling between modes via the macroscopic polarization field results in a transfer of oscillator strength building a "giant" LO oscillation.
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The document summarizes photoluminescence and reflectivity measurements of MgxZnyCd1–x–ySe epitaxial layers with varying Mg content (x). As Mg content increases, significant emission line broadening, an increase in activation energy, and a large Stokes shift are observed. For samples with high Mg content (x > 0.3), an anomalous temperature dependence of emission energy and line broadening is seen, attributed to exciton localization. Exciton localization on statistical CdSe clusters within the alloy is proposed as the most likely localization mechanism.
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Percolation-based vibrational picture to estimate nonrandom N substitution in...Oleg Maksimov
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2. 4260 Appl. Phys. Lett., Vol. 77, No. 26, 25 December 2000 Luo et al.
FIG. 2. ͑Color͒ Room temperature micro-PL spectra of three patterned QW
regions grown on a single InP substrate. The inset is a photograph of the
surface PL emission. The QWs are patterned to form three small squares
each emitting at a different wavelength, one red, one yellow, and one green.
shadow mask SAE for the QW integration. After the growth
of the buffer layers and the flat ZnCdMgSe bottom barrier
FIG. 1. ͑Color͒ ͑a͒ Schematic of the integrated ͑monolithic͒ three-color layer, the shadow mask is placed and one set of patterned
quantum well structure grown. ͑b͒ Illustration of the sequential step SAE ZnCdSe QW is grown ͑i͒. The mask can then be moved
process used. relative to the substrate and the second set of patterned
ZnCdSe QW is deposited adjacent to the first one ͑ii͒. The
acterize these patterned QW structures. Well-defined emis- third ZnCdSe QW can be grown in the same manner, after
sion in the red, yellow, and green was observed from the the second one ͑iii͒. The mask can then be removed and the
different patterned regions. top ZnCdMgSe barrier layer can be grown over the entire
The growth was performed by shadow mask SAE in a surface. In this way, regions with different color QWs are
Riber 2300P MBE system that consists of two growth cham- combined ͑i.e., integrated͒ on a single substrate. A uniform
bers connected by ultrahigh vacuum ͑UHV͒ modules. One ZnSe cap layer of ϳ6 nm thick is grown to protect the
chamber is dedicated to the growth of II–VI materials and ZnCdMgSe layer from oxidation.
the other to III–Vs. A specially designed mask and mask Micro-PL measurements were performed to characterize
fixture were used to perform this work.9 The mask fixture these integrated ZnCdSe/ZnCdMgSe patterned QWs. The
allows the mask to be placed and removed from the substrate measurement was done using a triple grating micro-
within the vacuum growth system so that multiple SAE steps Raman/PL spectrometer ͑JY-64000͒. The 488 nm line of an
can be performed sequentially. The structures were grown on argon ion laser was used as excitation with spot size of 2–3
semi-insulating InP͑100͒ substrates that were deoxidized in m. Figure 2 shows the room temperature micro-PL spectra
the III–V chamber under an As overpressure. A lattice- obtained from three patterned QW regions having different
matched InGaAs buffer layer was grown under conventional emission wavelengths. The peaks are centered at around 544,
MBE growth conditions to improve surface morphology. 585, and 628 nm with full widths at half maxima of 24, 19,
The sample was then transferred to the II–VI chamber in and 29 nm, respectively. The relative intensities from the
UHV, where a ϳ10 nm ZnCdSe low-temperature ͑LT͒ three QWs are similar, indicating that the QWs are of com-
buffer layer was grown at 170 °C.10 The Zn and Cd fluxes parable quality. This implies that the quality of the QW re-
had previously been adjusted to calibrate the composition of gion grown first does not degrade during the growth inter-
the ZnCdMgSe and ZnCdSe layers so that they were lattice ruption, the multiple mask replacements and the deposition
matched to the InP substrate and had the desired band gap. steps needed to grow the other two QWs. The variation in
The ZnCdSe LT buffer layer was followed by a 0.5-m- linewidth of the three regions is consistent with the different
thick ZnMgCdSe barrier layer grown at 250 °C with a band QW layer properties. The broader emission line is obtained
gap of 2.8 eV. The three patterned ZnCdSe/ZnCdMgSe QWs from the red QW, which is highly strained and possibly par-
were then grown sequentially on the different areas of the tially relaxed. By adjusting the ZnCdSe composition and the
barrier layer using the multiple-step SAE process described thickness, a pseudomorphic QW can be designed for emis-
later. Two ZnCdSe QWs, nominally 2 and 6 nm, were grown sion at this wavelength.11 The other two QWs are lattice
lattice-matched to InP to produce emission in the blue and matched and thus have narrower linewidths. Of the two, the
green regions. The third QW, nominally 10 nm thick, was yellow QW is the thicker one, which results in a narrower
grown with a higher Cd concentration (⌬a/a of ϳ1.8% to emission spectrum due to the reduced effect of thickness
InP͒ in order to obtain red emission. A schematic of the full fluctuations and interface roughness. Based on the PL emis-
structure grown is shown in Fig. 1͑a͒. sion wavelengths obtained we conclude that the actual QW
Figure 1͑b͒ illustrates the application of sequential thickness obtained were somewhat larger than intended. Blue
Downloaded 21 Aug 2001 to 146.95.156.66. Redistribution subject to AIP license or copyright, see http://ojps.aip.org/aplo/aplcr.jsp
3. Appl. Phys. Lett., Vol. 77, No. 26, 25 December 2000 Luo et al. 4261
are present. Similar results were obtained from the other two
regions.
The growth of these three different ZnCdSe/ZnCdMgSe
QWs on a single InP substrate illustrates the potential of this
material and demonstrates the feasibility of using shadow
mask SAE to fabricate integrated full color displays based on
the ZnCdMgSe material system. By doping the two barrier
layers ͑one n type and one p type͒ and growing a top highly
p-type doped ZnSeTe contact layer, LEDs could be made
from the patterned regions and units such as those shown in
Fig. 2 could be fabricated into full color LED display ele-
ments and white light sources. Furthermore, since R – G – B
lasing has been observed from these materials, integrated
full-color display elements based on semiconductor lasers
can also be considered. Currently, no other semiconductor
materials are available for this application.
In summary, integration of patterned multicolored
FIG. 3. Room temperature micro-PL spectra taken at four different positions
in a patterned QW stripe. The positions are indicated schematically in the
ZnCdSe/ZnCdMgSe QWs has been performed using shadow
right-side inset. The left-side inset shows the relative intensities of the PL mask SAE. Patterned ZnCdSe/ZnCdMgSe QWs with differ-
emission at the four positions. ent thickness and Cd compositions, which exhibit excitonic
emission in the red, green, and yellow regions, have been
grown on a single InP substrate. Excellent optical properties
emission can be obtained by growing a thinner lattice-
were obtained from the integrated patterned QW regions.
matched ZnCdSe QW layer.12
These results demonstrate the potential of the ͑Zn, Cd,
The inset of Fig. 2 is a photograph of the sample surface
Mg͒Se material system and the use of shadow mask SAE
that shows three square-shaped ZnCdSe QW patterned re-
technique for integrated full-color (R – G – B) LED and
gions emitting at different wavelengths, located near each
laser-based display applications.
other on the InP substrate. It was taken by a conventional
photographic camera, observing through a microscope objec- The authors acknowledge the National Science Founda-
tive for magnification, while the sample surface was exposed tion through Grant No. ECS-9707213 for support of this re-
to the excitation laser ͑frequency-tripled Nd:yttrium– search. This work was performed under the auspices of the
aluminum–garnet laser at 355 nm͒ in a conventional PL New York State Center for Advanced Technology ͑CAT͒ on
setup, thus the color seen is the color of the PL emission. Ultrafast Photonic Materials and Applications. The authors
The squares are about 50 mϫ50 m and they are separated also acknowledge support from the Center for Analysis of
by ϳ500 m from each other. Each of the squares exhibits Structures and Interfaces ͑CASI͒ at City College.
different emission wavelength range: one in the red, one in
the yellow, and one in the green. The slightly distorted colors
of the three squares ͑compared to the spectra shown in Figs. 1
K. Koga and T. Yamaguchi, Prog. Cryst. Growth Charact. 23, 127 ͑1991͒.
2
2 and 3͒ are most likely due to artifacts caused by the expo- L. Zeng, B. X. Yang, A. Cavus, W. Lin, Y. Y. Luo, M. C. Tamargo, Y.
Guo, and Y. C. Chen, Appl. Phys. Lett. 72, 3136 ͑1998͒.
sure of the film. 3
W. Lin, B. X. Yang, S. P. Guo, A. Elmoumni, F. Fernandez, and M. C.
The lateral thickness and compositional variations of the Tamargo, Appl. Phys. Lett. 75, 2608 ͑1999͒.
4
patterned ZnCdSe/ZnCdMgSe QW structures were also M. C. Tamargo, W. Lin, S. P. Guo, Y. Luo, Y. Guo, and Y. C. Chen, J.
probed by micro-PL. The QW emission from a single 50 m Cryst. Growth 214Õ215, 1058 ͑2000͒.
5
A. J. Steckl and J. M. Zavada, MRS Bull. 24, 33 ͑1999͒.
wide stripe was measured at several positions along the 6
A. Y. Cho and F. K. Reinhart, Appl. Phys. Lett. 56, 2304 ͑1990͒.
stripe width. Figure 3 shows the results from a stripe having 7
T. Katsuyama, M. A. Tischler, D. J. Moore, and S. M. Bedair, J. Cryst.
emission at 585 nm. The inset shows the positions within the Growth 77, 85 ͑1986͒.
8
H. Saito, I. Ogura, Y. Sugimoto, and K. Kasahara, Appl. Phys. Lett. 66,
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10
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the stripe ͑plot No. 4͒ shows a reduced intensity. However, 11
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