Heterostructures by Shanmuk.pptx
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1) Heterostructures involve combining two semiconductors to form a junction that separates photogenerated electron-hole pairs, reducing recombination. In a type II staggered gap structure, electrons transfer to the conduction band of one semiconductor while holes transfer to the valence band of the other for improved separation. 2) There are several schemes for heterostructure photocatalysis, including Z-scheme, S-scheme, and solid-state variants involving acceptor and donor ions or additional semiconductors. These schemes facilitate inter-semiconductor charge transfer to drive oxidation and reduction reactions. 3) Proper band alignment and interface engineering are necessary to promote efficient charge separation and transfer across semiconductor junctions for photocatal
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3) Factors like internal resistance and surface chemistry effects cause the terminal voltage to differ from the theoretical voltage. Battery models account for these factors.
Lecture 4 4521 semiconductor device physics - metal-semiconductor system
This document discusses metal-semiconductor contacts and junctions. It provides figures from the textbook explaining the band diagrams and behavior of Ohmic contacts, Schottky contacts, and pn junction diodes. It addresses questions about deriving analytic models for the I-V characteristics and small-signal models of these devices based on their band structures and transport mechanisms.
Lead Acid Battery Lecture.pdf
The document provides information about lead-acid batteries, including:
1. It describes the basic construction of lead-acid batteries using lead and lead dioxide electrodes separated by a sulfuric acid electrolyte.
2. It explains the electrochemical reactions that occur during charging and discharging, where electrons are transferred between the electrodes through the external circuit.
3. It discusses factors that influence the battery voltage such as the electrolyte concentration, state of charge, and internal resistances, as well as models for predicting voltage.
Chap-4 Modern theory of solids.pptx
The document discusses molecular orbital theory of bonding in hydrogen molecules. It explains how the bonding molecular orbital is formed from the linear combination of atomic orbitals of the two hydrogen atoms. As the hydrogen atoms approach each other, their atomic orbitals overlap to form the lower energy bonding molecular orbital which is filled by the two electrons, and the higher energy antibonding molecular orbital which remains empty. A diagram and energy level diagram are provided to illustrate this process.
Ete411 Lec14
Lecture on Introduction of Semiconductor at North South University as the undergraduate course (ETE411)
=======================
Dr. Mashiur Rahman
Assistant Professor
Dept. of Electrical Engineering and Computer Science
North South University, Dhaka, Bangladesh
http://mashiur.biggani.org
ENGINEERING CHEMISTRY- Solved Model question paper,2017-18
This document contains the solved question paper for Engineering Chemistry. It discusses several topics:
1. The derivation of the Nernst equation for single electrode potential and its relationship to Gibbs free energy.
2. Concentration cells and calculating concentrations from cell potential.
3. The construction and working of a methanol-oxygen fuel cell.
4. The construction, working, and applications of lithium-ion batteries.
5. Key battery characteristics like cell potential, capacity, and cycle life.
6. The construction and advantages of a calomel reference electrode.
Ch1 slides-1
This document provides an overview of key concepts in semiconductor physics. It begins by introducing the crystal structure of silicon and how dopants can create an excess or deficiency of electrons (N-type or P-type silicon). It then discusses the energy band model and defines important terms like the band gap, Fermi energy level, density of states, and thermal equilibrium. The document derives expressions for the concentrations of electrons and holes as a function of doping, temperature, and the Fermi level position. It also examines intrinsic carrier concentration and how doping affects charge neutrality. Overall, the document establishes fundamental principles for understanding how electrons and holes behave in semiconductors.
Band theory
This document discusses band theory and several models used to describe electron behavior in solids, including the free electron model, nearly free electron model, and tight binding model. It provides an overview of each model, including their assumptions and how they describe properties like electron energy and band gaps. The free electron model treats electrons as independent particles but fails to explain material properties. The nearly free electron model incorporates a periodic potential and allows electron wavefunctions and energy bands to be described. The tight binding model uses a superposition of atomic orbitals to approximate electron wavefunctions in solids where potential is strong.
Elec3908 lect 3
This lecture discusses energy band diagrams and doping of semiconductors. It introduces energy band diagrams as a way to represent carrier energy in semiconductors. Intrinsic semiconductors have equal numbers of electrons and holes, while doping with impurities creates excess carriers by introducing donors or acceptors. N-type doping uses group V donors to generate excess electrons, while p-type uses group III acceptors to generate excess holes. Doping allows tailoring of semiconductor properties for device applications.
Inorganic materials Part 2/2
(1) The document discusses doping of semiconductors and transition metal oxides, including n-type and p-type doping of silicon. It also covers band structure diagrams and density of states plots.
(2) Preparation methods for metal oxides include molecular synthesis and solid state synthesis. Modification of solids can occur through ion exchange or intercalation. Lithium ion batteries operate through lithium intercalation into graphite.
(3) Characterization techniques covered are XRD for crystal structure analysis and electron microscopy. Magnetic properties depend on temperature; ferromagnets become paramagnetic above the Curie temperature. Spinels can exhibit ferrimagnetism from opposing sublattice
1-2015_pv_principles2.pptx
The document provides an overview of photovoltaic concepts and systems. It begins with a brief history of early photovoltaic cells developed at Bell Labs in 1954 with 6% efficiency. It then covers fundamental concepts such as energy bands in semiconductors, doping, space charge layers, p-n junctions, and how different types of photovoltaic cells work. The document discusses limitations of single junction cells and ways to overcome them, such as multi-junction cells. It provides examples of different generations of photovoltaic technologies and discusses improving efficiency and commercial viability.
IB Chemistry on Lewis structure, ionic and covalent bonding
1. The document discusses different types of bonding including ionic bonding, covalent bonding, and dative bonding.
2. Ionic bonding occurs between metals and nonmetals where the metal loses electrons and forms cations and the nonmetal gains electrons and forms anions.
3. Covalent bonding occurs between nonmetals where electrons are shared between atoms to achieve stable octets. Single, double, and triple covalent bonds are formed by sharing one, two, or three electron pairs.
лекция 1 обзор методов вычислительной физики
The document discusses multi-scale modeling of radiation effects in dielectric materials. It summarizes:
1. First-principles quantum mechanical methods are used to simulate defect formation and electronic structure changes at the atomic scale.
2. A quantum transport model calculates current-voltage characteristics based on the defect states. This shows good agreement with experimental I-V curves.
3. A percolation model extends the simulations to larger device scales by parameterizing the defect properties from the smaller scale calculations. This allows modeling transient current behavior over nanosecond timescales.
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Lecture-MOS Capacitors basic for MOSFET.pdf.pdf
The document discusses a metal-oxide-semiconductor (MOS) capacitor. It describes the structure of an MOS capacitor, which consists of a metal gate electrode, insulating oxide layer, and doped semiconductor substrate. Depending on the applied gate voltage VG, the semiconductor near the interface can accumulate charge, deplete charge, or invert and accumulate the opposite charge type. The document provides quantitative equations to model the electrostatic potential and charge distribution within the semiconductor as a function of VG. It also relates VG to the potential drops across the oxide and semiconductor regions.
Similar to Heterostructures by Shanmuk.pptx (20)
Lecture 4 4521 semiconductor device physics - metal-semiconductor system
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ENGINEERING CHEMISTRY- Solved Model question paper,2017-18
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Recently uploaded
The debris of the ‘last major merger’ is dynamically young
The Milky Way’s (MW) inner stellar halo contains an [Fe/H]-rich component with highly eccentric orbits, often referred to as the
‘last major merger.’ Hypotheses for the origin of this component include Gaia-Sausage/Enceladus (GSE), where the progenitor
collided with the MW proto-disc 8–11 Gyr ago, and the Virgo Radial Merger (VRM), where the progenitor collided with the
MW disc within the last 3 Gyr. These two scenarios make different predictions about observable structure in local phase space,
because the morphology of debris depends on how long it has had to phase mix. The recently identified phase-space folds in Gaia
DR3 have positive caustic velocities, making them fundamentally different than the phase-mixed chevrons found in simulations
at late times. Roughly 20 per cent of the stars in the prograde local stellar halo are associated with the observed caustics. Based
on a simple phase-mixing model, the observed number of caustics are consistent with a merger that occurred 1–2 Gyr ago.
We also compare the observed phase-space distribution to FIRE-2 Latte simulations of GSE-like mergers, using a quantitative
measurement of phase mixing (2D causticality). The observed local phase-space distribution best matches the simulated data
1–2 Gyr after collision, and certainly not later than 3 Gyr. This is further evidence that the progenitor of the ‘last major merger’
did not collide with the MW proto-disc at early times, as is thought for the GSE, but instead collided with the MW disc within
the last few Gyr, consistent with the body of work surrounding the VRM.
EWOCS-I: The catalog of X-ray sources in Westerlund 1 from the Extended Weste...
Context. With a mass exceeding several 104 M⊙ and a rich and dense population of massive stars, supermassive young star clusters
represent the most massive star-forming environment that is dominated by the feedback from massive stars and gravitational interactions
among stars.
Aims. In this paper we present the Extended Westerlund 1 and 2 Open Clusters Survey (EWOCS) project, which aims to investigate
the influence of the starburst environment on the formation of stars and planets, and on the evolution of both low and high mass stars.
The primary targets of this project are Westerlund 1 and 2, the closest supermassive star clusters to the Sun.
Methods. The project is based primarily on recent observations conducted with the Chandra and JWST observatories. Specifically,
the Chandra survey of Westerlund 1 consists of 36 new ACIS-I observations, nearly co-pointed, for a total exposure time of 1 Msec.
Additionally, we included 8 archival Chandra/ACIS-S observations. This paper presents the resulting catalog of X-ray sources within
and around Westerlund 1. Sources were detected by combining various existing methods, and photon extraction and source validation
were carried out using the ACIS-Extract software.
Results. The EWOCS X-ray catalog comprises 5963 validated sources out of the 9420 initially provided to ACIS-Extract, reaching a
photon flux threshold of approximately 2 × 10−8 photons cm−2
s
−1
. The X-ray sources exhibit a highly concentrated spatial distribution,
with 1075 sources located within the central 1 arcmin. We have successfully detected X-ray emissions from 126 out of the 166 known
massive stars of the cluster, and we have collected over 71 000 photons from the magnetar CXO J164710.20-455217.
Compexometric titration/Chelatorphy titration/chelating titration
Classification
Metal ion ion indicators
Masking and demasking reagents
Estimation of Magnisium sulphate
Calcium gluconate
Complexometric Titration/ chelatometry titration/chelating titration, introduction, Types-
1.Direct Titration
2.Back Titration
3.Replacement Titration
4.Indirect Titration
Masking agent, Demasking agents
formation of complex
comparition between masking and demasking agents,
Indicators/Metal ion indicators/ Metallochromic indicators/pM indicators,
Visual Technique,PM indicators (metallochromic), Indicators of pH, Redox Indicators
Instrumental Techniques-Photometry
Potentiometry
Miscellaneous methods.
Complex titration with EDTA.
Farming systems analysis: what have we learnt?.pptx
Presentation given at the official farewell of Prof Ken Gillet at Wageningen on 13 June 2024
Sexuality - Issues, Attitude and Behaviour - Applied Social Psychology - Psyc...
A proprietary approach developed by bringing together the best of learning theories from Psychology, design principles from the world of visualization, and pedagogical methods from over a decade of training experience, that enables you to: Learn better, faster!
ESA/ACT Science Coffee: Diego Blas - Gravitational wave detection with orbita...
ESA/ACT Science Coffee: Diego Blas - Gravitational wave detection with orbita...Advanced-Concepts-Team
Presentation in the Science Coffee of the Advanced Concepts Team of the European Space Agency on the 07.06.2024.
Speaker: Diego Blas (IFAE/ICREA)
Title: Gravitational wave detection with orbital motion of Moon and artificial
Abstract:
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学校原件一模一样【微信：741003700 】《(salfor毕业证书)索尔福德大学毕业证》【微信：741003700 】学位证，留信认证（真实可查，永久存档）原件一模一样纸张工艺/offer、雅思、外壳等材料/诚信可靠,可直接看成品样本，帮您解决无法毕业带来的各种难题！外壳，原版制作，诚信可靠，可直接看成品样本。行业标杆！精益求精，诚心合作，真诚制作！多年品质 ,按需精细制作，24小时接单,全套进口原装设备。十五年致力于帮助留学生解决难题，包您满意。
本公司拥有海外各大学样板无数，能完美还原。
1:1完美还原海外各大学毕业材料上的工艺：水印，阴影底纹，钢印LOGO烫金烫银，LOGO烫金烫银复合重叠。文字图案浮雕、激光镭射、紫外荧光、温感、复印防伪等防伪工艺。材料咨询办理、认证咨询办理请加学历顾问Q/微741003700
【主营项目】
一.毕业证【q微741003700】成绩单、使馆认证、教育部认证、雅思托福成绩单、学生卡等！
二.真实使馆公证(即留学回国人员证明,不成功不收费)
三.真实教育部学历学位认证（教育部存档！教育部留服网站永久可查）
四.办理各国各大学文凭(一对一专业服务,可全程监控跟踪进度)
如果您处于以下几种情况：
◇在校期间，因各种原因未能顺利毕业……拿不到官方毕业证【q/微741003700】
◇面对父母的压力，希望尽快拿到；
◇不清楚认证流程以及材料该如何准备；
◇回国时间很长，忘记办理；
◇回国马上就要找工作，办给用人单位看；
◇企事业单位必须要求办理的
◇需要报考公务员、购买免税车、落转户口
◇申请留学生创业基金
留信网认证的作用:
1:该专业认证可证明留学生真实身份
2:同时对留学生所学专业登记给予评定
3:国家专业人才认证中心颁发入库证书
4:这个认证书并且可以归档倒地方
5:凡事获得留信网入网的信息将会逐步更新到个人身份内，将在公安局网内查询个人身份证信息后，同步读取人才网入库信息
6:个人职称评审加20分
7:个人信誉贷款加10分
8:在国家人才网主办的国家网络招聘大会中纳入资料，供国家高端企业选择人才
8.Isolation of pure cultures and preservation of cultures.pdf
Isolation of pure culture, its various method.
快速办理(UAM毕业证书)马德里自治大学毕业证学位证一模一样
学校原件一模一样【微信：741003700 】《(UAM毕业证书)马德里自治大学毕业证学位证》【微信：741003700 】学位证，留信认证（真实可查，永久存档）原件一模一样纸张工艺/offer、雅思、外壳等材料/诚信可靠,可直接看成品样本，帮您解决无法毕业带来的各种难题！外壳，原版制作，诚信可靠，可直接看成品样本。行业标杆！精益求精，诚心合作，真诚制作！多年品质 ,按需精细制作，24小时接单,全套进口原装设备。十五年致力于帮助留学生解决难题，包您满意。
本公司拥有海外各大学样板无数，能完美还原。
1:1完美还原海外各大学毕业材料上的工艺：水印，阴影底纹，钢印LOGO烫金烫银，LOGO烫金烫银复合重叠。文字图案浮雕、激光镭射、紫外荧光、温感、复印防伪等防伪工艺。材料咨询办理、认证咨询办理请加学历顾问Q/微741003700
【主营项目】
一.毕业证【q微741003700】成绩单、使馆认证、教育部认证、雅思托福成绩单、学生卡等！
二.真实使馆公证(即留学回国人员证明,不成功不收费)
三.真实教育部学历学位认证（教育部存档！教育部留服网站永久可查）
四.办理各国各大学文凭(一对一专业服务,可全程监控跟踪进度)
如果您处于以下几种情况：
◇在校期间，因各种原因未能顺利毕业……拿不到官方毕业证【q/微741003700】
◇面对父母的压力，希望尽快拿到；
◇不清楚认证流程以及材料该如何准备；
◇回国时间很长，忘记办理；
◇回国马上就要找工作，办给用人单位看；
◇企事业单位必须要求办理的
◇需要报考公务员、购买免税车、落转户口
◇申请留学生创业基金
留信网认证的作用:
1:该专业认证可证明留学生真实身份
2:同时对留学生所学专业登记给予评定
3:国家专业人才认证中心颁发入库证书
4:这个认证书并且可以归档倒地方
5:凡事获得留信网入网的信息将会逐步更新到个人身份内，将在公安局网内查询个人身份证信息后，同步读取人才网入库信息
6:个人职称评审加20分
7:个人信誉贷款加10分
8:在国家人才网主办的国家网络招聘大会中纳入资料，供国家高端企业选择人才
Randomised Optimisation Algorithms in DAPHNE
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Austrian-Slovenian HPC Meeting 2024 – ASHPC24, Seeblickhotel Grundlsee in Austria, 10–13 June 2024
https://ashpc.eu/
waterlessdyeingtechnolgyusing carbon dioxide chemicalspdf
The technology uses reclaimed CO₂ as the dyeing medium in a closed loop process. When pressurized, CO₂ becomes supercritical (SC-CO₂). In this state CO₂ has a very high solvent power, allowing the dye to dissolve easily.
Applied Science: Thermodynamics, Laws & Methodology.pdf
When I was asked to give a companion lecture in support of ‘The Philosophy of Science’ (https://shorturl.at/4pUXz) I decided not to walk through the detail of the many methodologies in order of use. Instead, I chose to employ a long standing, and ongoing, scientific development as an exemplar. And so, I chose the ever evolving story of Thermodynamics as a scientific investigation at its best.
Conducted over a period of >200 years, Thermodynamics R&D, and application, benefitted from the highest levels of professionalism, collaboration, and technical thoroughness. New layers of application, methodology, and practice were made possible by the progressive advance of technology. In turn, this has seen measurement and modelling accuracy continually improved at a micro and macro level.
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aziz sancar nobel prize winner: from mardin to nobel
aziz sancar nobel prize winner: from mardin to nobel
The debris of the ‘last major merger’ is dynamically young
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Farming systems analysis: what have we learnt?.pptx
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8.Isolation of pure cultures and preservation of cultures.pdf
8.Isolation of pure cultures and preservation of cultures.pdf
waterlessdyeingtechnolgyusing carbon dioxide chemicalspdf
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Heterostructures by Shanmuk.pptx
- 1. Basics of Heterostructure for Photocatalysis T. Shanmuka Rao
- 2. Abbreviations used in this PPT SC – Semiconductor m – Metal CB – Conduction Band VB – Valence Band BIEF – Built In Electric Field
- 3. * Photocatalysis Rakshit Ameta1 , Meenakshi S. Solanki2 , Surbhi Benjamin3 and Suresh C. Ameta. Ef Ef SC I SC II Before contact Electron hoop is due to the difference in the fermi level ( high fermi to low fermi level) or ( low to high workfunction semiconductor) and hole do opposite. e- h+ Electron hooping Hole hooping Hopping not possible Allowed transitions CB VB Ef Vacuum Electron affinity (χ) Workfunction (φ) Eg Basics
- 4. Growth techniques Ef Ef SC I SC II Before contact After contact SC I SC II e- SC I SC II Efc - - Built In Electric Field (BIEF) F = qE + + + - Basic mechanism of heterostructures * Engineering interface structures for heterojunction photocatalysts Min Lin,†ab Hui Chen,†ab Zizhong Zhang *ab and Xuxu Wang. Efc e- e- e- e- h+ h+ h+ h+ Type I Straddling gap Reduction Oxidation
- 5. Ef Ef SC I SC II Before contact Ef Ef SC I SC II Type III Broken gap No electron hole pair separation in type III heterostructures Type II Staggered Gap Efc e- e- e- e- h+ h+ h+ h+ Reduction Oxidation
- 6. * S-Scheme Heterojunction Photocatalyst Quanlong Xu,1,2,4 Liuyang Zhang,1,4 Bei Cheng,1 Jiajie Fan,3 and Jiaguo Yu1,5. Comparison between Type I and II heterostructure Efc e- e- e- e- h+ h+ h+ h+ Type I Straddling gap Electron and hole pair in single semiconductor high chances of recombination Low redox ability Oxidation Reduction Type II Staggered Gap Efc e- e- e- e- h+ h+ h+ h+ • Better heterojunction for electron and hole separation compared to type I and III. • Also problem in redox ability because reduction potential should be more negative and oxidation level should be more positive vs NHE. Oxidation Reduction
- 7. Ef Ef SC I SC II Metal nanoparticle eg: Ag, Au, Pt etc. Its very difficult to synthesis nanoparticles exactly in between two semiconductors. Ef All Solid State Z - scheme These acceptor and donor ions will make some unusual reactions in the solution. Also this system will work in acidic mediums. Reaction A + e- = D D + h+ = A. Traditional Z - scheme Efc e- e- e- e- h+ h+ h+ h+ A D Oxidation Reduction
- 8. Ef Ef SC I SC II Before contact Ef Ef SC I SC II Before contact Both schemes are good for charge separation as well as redox abilities Z - scheme Efc e- e- e- e- h+ h+ h+ h+ Oxidation Reduction Step (S) - scheme Efc e- e- e- e- h+ h+ h+ h+ Oxidation Reduction
- 9. Before contact EfS Efm Metal Semiconductor Schottky scheme Efc CB VB CB VB Semiconductor Metal Ohm scheme Efc Semiconductor Metal Before contact EfS Efm Metal Semiconductor VB CB VB CB (φm) (φsc) (φsc) (φm)
- 10. References Engineering interface structures for heterojunction photocatalysts Min Lin, Hui Chen, Zizhong Zhang and Xuxu Wang, Phys. Chem. Chem. Phys., 2023, 25, 4388. Heterojunction Photocatalysts Jingxiang Low, Jiaguo Yu,* Mietek Jaroniec, Swelm Wageh, and Ahmed A. Al-Ghamdi, Adv. Mater. 2017, 1601694. S-Scheme Heterojunction Photocatalyst Quanlong Xu, Liuyang Zhang, Bei Cheng, Jiajie Fan, and Jiaguo Yu, Chem 6, 1543–1559, July 9, 2020 ª 2020 Elsevier Inc.
- 11. Thank You