ρ ρ LED access resistances d A W d s n s p p p W the output window size p-layer d p series access resistance d n n-layer series access resistance

Size: px
Start display at page:

Download "ρ ρ LED access resistances d A W d s n s p p p W the output window size p-layer d p series access resistance d n n-layer series access resistance"

Transcription

1 LED access resistances W the output window size p-layer series access resistance d p n-layer series access resistance d n The n-layer series access resistance R = ρ s n where the resistivity of the n-layer is ρ n, the thickness is d n and the contact area is A The p-layer series access resistance (for rectangular W x W window) n R d n A W 2 1 / ρ ρ W d = 2d s p p p p p 1

2 I-V characteristics of real LEDs The I-V characteristic of the p-n junction: qv j I= IS exp 1 kt V j is the voltage drop across the p-n junction itself. In addition, there is a voltage drop across the series access resistances: V s-n = I R s-n ; V s-p = I R s-p ; where d R n s n = ρ n A R s p p ρ 1 2d p The total voltage drop across the LED: V = V j + V sn + V sp ; The LED current is controlled by the junction voltage V j : V j = V - V sn -V sp ; qv ( I Rs ) The real LED I-V: I= IS exp 1 kt R s is the total access series resistance. R s = R s-n +R s-p + R contact 2

3 High efficiency heterostructure LEDs All the LEDs considered in above lectures utilized the p-n junctions formed of the same material on the n- and p-sides. In these, so-called homojunctions, the potential barriers controlling the electron and hole currents are only due to the difference in the material doping (impurity concentrations on the n- and p-sides). Major issues in regular (homojunction) LEDs: 1.Very high concentration of electrons and holes is hardly achievable due to diffusion (the characteristic length of injected carrier distribution is L n or L P. 2.The access regions of LED absorb the light generated at the p-n junction; thinning the access regions increases access resistance. 3.To achieve high injection levels, very high doping is needed. This worsen material quality and reduces efficiency; it also further increases the absorption. 3

4 In the heterojunctions, the potential barriers for electrons and for holes can be different Example: undoped AlGaAs/GaAs heterostructure creates different barriers for the electrones and for the holes at the hetero-interface barrier for electrons For GaAs, E G = 1.42 ev; For AlAs, E G = 2.18 ev For Al x Ga 1-x As, E G = x (x < 0.45) barrier for electrons 4

5 p-n heterojunctions In the p-n heterojunction, the potential barriers for electrons and holes are determined by both the composition and the doping difference p-n homojunction from materials 2 p-n homojunction from materials 1 5

6 Double heterojunction (DH) LED structure Typical AlGaAs/GaAs DH LED structure could be i (undoped) region as well AlGaAs (barrier) GaAs (LED active region) AlGaAs (barrier) 6

7 Dramatic increase in the extraction efficiency: DH LEDs with wide-bandgap cladding layers Zero bias E g2 > E g1 n E g2 > E g1 p E g1 Forward bias 7

8 DH LEDs Homojunction and DH LEDs under forward bias Typically, W DH << L n, L P After F.Schubert, Light-Emitting-Diodes-dot-org 8

9 DH LEDs At very high forward bias: Є C Є Fn Є Fp Є V n, p p(x) regular LED n(x) regular LED 9

10 DH LEDs The active region of DH LEDs forms a so-called quantum well In the quantum well, electrons and holes are strongly confined. Therefore, the recombination rate, R ~ n x p, increases significantly 10

11 Advantages of DH LEDs 1. Both n- and p- regions are made out of widebandgap materials (ε G > hν), therefore there is no absorption in these regions: they form optical windows 2. n- and p- regions can be highly doped. 3. Injected electrons and holes are confined in a very narrow active region (quantum well) where the n x p product is extremely high. Therefore, the radiative recombination rate, R, is high. 11

12 DH LEDs confinement issue Effect of electric field on electron hole confinement and recombination No electric field Electric field applied hν ε G Under electric field applied the electrons and holes are partially separated. This decreases the recombination efficiency and creates so-called red-shift of the emission. The QW thickness in DH-LEDs must be kept small enough. 12

13 Multiple Quantum Well LEDs The total number of energy states in the quantum well is limited. Therefore, at high injection currents, all the states available can be occupied by electrons. This will saturate the optical power. Increasing the QW thickness is not practical as it reduces the confinement. Multiple Quantum Well (MQW) structure overcomes this problem 13

Laser Diodes. Revised: 3/14/14 14: , Henry Zmuda Set 6a Laser Diodes 1

Laser Diodes. Revised: 3/14/14 14: , Henry Zmuda Set 6a Laser Diodes 1 Laser Diodes Revised: 3/14/14 14:03 2014, Henry Zmuda Set 6a Laser Diodes 1 Semiconductor Lasers The simplest laser of all. 2014, Henry Zmuda Set 6a Laser Diodes 2 Semiconductor Lasers 1. Homojunction

More information

Chapter 5. Semiconductor Laser

Chapter 5. Semiconductor Laser Chapter 5 Semiconductor Laser 5.0 Introduction Laser is an acronym for light amplification by stimulated emission of radiation. Albert Einstein in 1917 showed that the process of stimulated emission must

More information

Semiconductor device structures are traditionally divided into homojunction devices

Semiconductor device structures are traditionally divided into homojunction devices 0. Introduction: Semiconductor device structures are traditionally divided into homojunction devices (devices consisting of only one type of semiconductor material) and heterojunction devices (consisting

More information

CME 300 Properties of Materials. ANSWERS: Homework 9 November 26, As atoms approach each other in the solid state the quantized energy states:

CME 300 Properties of Materials. ANSWERS: Homework 9 November 26, As atoms approach each other in the solid state the quantized energy states: CME 300 Properties of Materials ANSWERS: Homework 9 November 26, 2011 As atoms approach each other in the solid state the quantized energy states: are split. This splitting is associated with the wave

More information

(b) Spontaneous emission. Absorption, spontaneous (random photon) emission and stimulated emission.

(b) Spontaneous emission. Absorption, spontaneous (random photon) emission and stimulated emission. Lecture 10 Stimulated Emission Devices Lasers Stimulated emission and light amplification Einstein coefficients Optical fiber amplifiers Gas laser and He-Ne Laser The output spectrum of a gas laser Laser

More information

EECE 4646 Optics for Engineers. Lecture 17

EECE 4646 Optics for Engineers. Lecture 17 C 4646 Optics for ngineers Lecture 7 9 March, 00 Spontaneous mission Rate BFOR MISSION DURING MISSION AFTR MISSION electron hν hν The rate of spontaneous emission r sp can be written as: A f r sp A f[

More information

Optoelectronics ELEC-E3210

Optoelectronics ELEC-E3210 Optoelectronics ELEC-E3210 Lecture 3 Spring 2017 Semiconductor lasers I Outline 1 Introduction 2 The Fabry-Pérot laser 3 Transparency and threshold current 4 Heterostructure laser 5 Power output and linewidth

More information

Stimulated Emission Devices: LASERS

Stimulated Emission Devices: LASERS Stimulated Emission Devices: LASERS 1. Stimulated Emission and Photon Amplification E 2 E 2 E 2 hυ hυ hυ In hυ Out hυ E 1 E 1 E 1 (a) Absorption (b) Spontaneous emission (c) Stimulated emission The Principle

More information

Introduction to Optoelectronic Device Simulation by Joachim Piprek

Introduction to Optoelectronic Device Simulation by Joachim Piprek NUSOD 5 Tutorial MA Introduction to Optoelectronic Device Simulation by Joachim Piprek Outline:. Introduction: VCSEL Example. Electron Energy Bands 3. Drift-Diffusion Model 4. Thermal Model 5. Gain/Absorption

More information

Schottky Diodes (M-S Contacts)

Schottky Diodes (M-S Contacts) Schottky Diodes (M-S Contacts) Three MITs of the Day Band diagrams for ohmic and rectifying Schottky contacts Similarity to and difference from bipolar junctions on electrostatic and IV characteristics.

More information

PHYSICAL ELECTRONICS(ECE3540) CHAPTER 9 METAL SEMICONDUCTOR AND SEMICONDUCTOR HETERO-JUNCTIONS

PHYSICAL ELECTRONICS(ECE3540) CHAPTER 9 METAL SEMICONDUCTOR AND SEMICONDUCTOR HETERO-JUNCTIONS PHYSICAL ELECTRONICS(ECE3540) CHAPTER 9 METAL SEMICONDUCTOR AND SEMICONDUCTOR HETERO-JUNCTIONS Tennessee Technological University Monday, November 11, 013 1 Introduction Chapter 4: we considered the semiconductor

More information

External (differential) quantum efficiency Number of additional photons emitted / number of additional electrons injected

External (differential) quantum efficiency Number of additional photons emitted / number of additional electrons injected Semiconductor Lasers Comparison with LEDs The light emitted by a laser is generally more directional, more intense and has a narrower frequency distribution than light from an LED. The external efficiency

More information

Typical example of the FET: MEtal Semiconductor FET (MESFET)

Typical example of the FET: MEtal Semiconductor FET (MESFET) Typical example of the FET: MEtal Semiconductor FET (MESFET) Conducting channel (RED) is made of highly doped material. The electron concentration in the channel n = the donor impurity concentration N

More information

Thermionic emission vs. drift-diffusion vs. p-n junction

Thermionic emission vs. drift-diffusion vs. p-n junction 6.772/SMA5111 - Compound Semiconductors Lecture 4 - Carrier flow in heterojunctions - Outline A look at current models for m-s junctions (old business) Thermionic emission vs. drift-diffusion vs. p-n junction

More information

Metal Vapour Lasers Use vapoured metal as a gain medium Developed by W. Silfvast (1966) Two types: Ionized Metal vapour (He-Cd) Neutral Metal vapour

Metal Vapour Lasers Use vapoured metal as a gain medium Developed by W. Silfvast (1966) Two types: Ionized Metal vapour (He-Cd) Neutral Metal vapour Metal Vapour Lasers Use vapoured metal as a gain medium Developed by W. Silfvast (1966) Two types: Ionized Metal vapour (He-Cd) Neutral Metal vapour (Cu) All operate by vaporizing metal in container Helium

More information

Chapter 1 Overview of Semiconductor Materials and Physics

Chapter 1 Overview of Semiconductor Materials and Physics Chapter 1 Overview of Semiconductor Materials and Physics Professor Paul K. Chu Conductivity / Resistivity of Insulators, Semiconductors, and Conductors Semiconductor Elements Period II III IV V VI 2 B

More information

Paper Review. Special Topics in Optical Engineering II (15/1) Minkyu Kim. IEEE Journal of Quantum Electronics, Feb 1985

Paper Review. Special Topics in Optical Engineering II (15/1) Minkyu Kim. IEEE Journal of Quantum Electronics, Feb 1985 Paper Review IEEE Journal of Quantum Electronics, Feb 1985 Contents Semiconductor laser review High speed semiconductor laser Parasitic elements limitations Intermodulation products Intensity noise Large

More information

Chapter 6: Light-Emitting Diodes

Chapter 6: Light-Emitting Diodes Chapter 6: Light-Emitting Diodes Photoluminescence and electroluminescence Basic transitions Luminescence efficiency Light-emitting diodes Internal quantum efficiency External quantum efficiency Device

More information

Physics of Semiconductors

Physics of Semiconductors Physics of Semiconductors 9 th 2016.6.13 Shingo Katsumoto Department of Physics and Institute for Solid State Physics University of Tokyo Site for uploading answer sheet Outline today Answer to the question

More information

Quantum and Non-local Transport Models in Crosslight Device Simulators. Copyright 2008 Crosslight Software Inc.

Quantum and Non-local Transport Models in Crosslight Device Simulators. Copyright 2008 Crosslight Software Inc. Quantum and Non-local Transport Models in Crosslight Device Simulators Copyright 2008 Crosslight Software Inc. 1 Introduction Quantization effects Content Self-consistent charge-potential profile. Space

More information

Lecture 5 Junction characterisation

Lecture 5 Junction characterisation Lecture 5 Junction characterisation Jon Major October 2018 The PV research cycle Make cells Measure cells Despair Repeat 40 1.1% 4.9% Data Current density (ma/cm 2 ) 20 0-20 -1.0-0.5 0.0 0.5 1.0 Voltage

More information

Lab #5 Current/Voltage Curves, Efficiency Measurements and Quantum Efficiency

Lab #5 Current/Voltage Curves, Efficiency Measurements and Quantum Efficiency Lab #5 Current/Voltage Curves, Efficiency Measurements and Quantum Efficiency R.J. Ellingson and M.J. Heben November 4, 2014 PHYS 4580, 6280, and 7280 Simple solar cell structure The Diode Equation Ideal

More information

Basic Principles of Light Emission in Semiconductors

Basic Principles of Light Emission in Semiconductors Basic Principles of Light Emission in Semiconductors Class: Integrated Photonic Devices Time: Fri. 8:00am ~ 11:00am. Classroom: 資電 06 Lecturer: Prof. 李明昌 (Ming-Chang Lee) Model for Light Generation and

More information

Electron Energy, E E = 0. Free electron. 3s Band 2p Band Overlapping energy bands. 3p 3s 2p 2s. 2s Band. Electrons. 1s ATOM SOLID.

Electron Energy, E E = 0. Free electron. 3s Band 2p Band Overlapping energy bands. 3p 3s 2p 2s. 2s Band. Electrons. 1s ATOM SOLID. Electron Energy, E Free electron Vacuum level 3p 3s 2p 2s 2s Band 3s Band 2p Band Overlapping energy bands Electrons E = 0 1s ATOM 1s SOLID In a metal the various energy bands overlap to give a single

More information

Laser Basics. What happens when light (or photon) interact with a matter? Assume photon energy is compatible with energy transition levels.

Laser Basics. What happens when light (or photon) interact with a matter? Assume photon energy is compatible with energy transition levels. What happens when light (or photon) interact with a matter? Assume photon energy is compatible with energy transition levels. Electron energy levels in an hydrogen atom n=5 n=4 - + n=3 n=2 13.6 = [ev]

More information

Recombination: Depletion. Auger, and Tunnelling

Recombination: Depletion. Auger, and Tunnelling Recombination: Depletion Region, Bulk, Radiative, Auger, and Tunnelling Ch 140 Lecture Notes #13 Prepared by David Gleason We assume: Review of Depletion Region Recombination Flat Quantum Fermi Levels

More information

Single Photon detectors

Single Photon detectors Single Photon detectors Outline Motivation for single photon detection Semiconductor; general knowledge and important background Photon detectors: internal and external photoeffect Properties of semiconductor

More information

MTLE-6120: Advanced Electronic Properties of Materials. Semiconductor p-n junction diodes. Reading: Kasap ,

MTLE-6120: Advanced Electronic Properties of Materials. Semiconductor p-n junction diodes. Reading: Kasap , MTLE-6120: Advanced Electronic Properties of Materials 1 Semiconductor p-n junction diodes Reading: Kasap 6.1-6.5, 6.9-6.12 Metal-semiconductor contact potential 2 p-type n-type p-type n-type Same semiconductor

More information

junctions produce nonlinear current voltage characteristics which can be exploited

junctions produce nonlinear current voltage characteristics which can be exploited Chapter 6 P-N DODES Junctions between n-and p-type semiconductors are extremely important foravariety of devices. Diodes based on p-n junctions produce nonlinear current voltage characteristics which can

More information

ECE-305: Spring 2018 Exam 2 Review

ECE-305: Spring 2018 Exam 2 Review ECE-305: Spring 018 Exam Review Pierret, Semiconductor Device Fundamentals (SDF) Chapter 3 (pp. 75-138) Chapter 5 (pp. 195-6) Professor Peter Bermel Electrical and Computer Engineering Purdue University,

More information

8. Schottky contacts / JFETs

8. Schottky contacts / JFETs Technische Universität Graz Institute of Solid State Physics 8. Schottky contacts / JFETs Nov. 21, 2018 Technische Universität Graz Institute of Solid State Physics metal - semiconductor contacts Photoelectric

More information

Introduction to Sources: Radiative Processes and Population Inversion in Atoms, Molecules, and Semiconductors Atoms and Molecules

Introduction to Sources: Radiative Processes and Population Inversion in Atoms, Molecules, and Semiconductors Atoms and Molecules OPTI 500 DEF, Spring 2012, Lecture 2 Introduction to Sources: Radiative Processes and Population Inversion in Atoms, Molecules, and Semiconductors Atoms and Molecules Energy Levels Every atom or molecule

More information

V BI. H. Föll: kiel.de/matwis/amat/semi_en/kap_2/backbone/r2_2_4.html. different electrochemical potentials (i.e.

V BI. H. Föll:  kiel.de/matwis/amat/semi_en/kap_2/backbone/r2_2_4.html. different electrochemical potentials (i.e. Consider the the band diagram for a homojunction, formed when two bits of the same type of semicondutor (e.g. Si) are doped p and ntype and then brought into contact. Electrons in the two bits have different

More information

Final Exam Solution, Spring Semester 2011 ECSE 6962, Light Emitting Diodes and Solid State Lighting (Prof. E. F. Schubert)

Final Exam Solution, Spring Semester 2011 ECSE 6962, Light Emitting Diodes and Solid State Lighting (Prof. E. F. Schubert) Final Exam Solution, Spring Semester 2011 ECSE 6962, Light Emitting Diodes and Solid State Lighting (Prof. E. F. Schubert) Note: Put your name on your paper. Show your work. Underline all results. Always

More information

n N D n p = n i p N A

n N D n p = n i p N A Summary of electron and hole concentration in semiconductors Intrinsic semiconductor: E G n kt i = pi = N e 2 0 Donor-doped semiconductor: n N D where N D is the concentration of donor impurity Acceptor-doped

More information

Lecture 17 - p-n Junction. October 11, Ideal p-n junction in equilibrium 2. Ideal p-n junction out of equilibrium

Lecture 17 - p-n Junction. October 11, Ideal p-n junction in equilibrium 2. Ideal p-n junction out of equilibrium 6.72J/3.43J - Integrated Microelectronic Devices - Fall 22 Lecture 17-1 Lecture 17 - p-n Junction October 11, 22 Contents: 1. Ideal p-n junction in equilibrium 2. Ideal p-n junction out of equilibrium

More information

Effective masses in semiconductors

Effective masses in semiconductors Effective masses in semiconductors The effective mass is defined as: In a solid, the electron (hole) effective mass represents how electrons move in an applied field. The effective mass reflects the inverse

More information

Schottky diodes. JFETs - MESFETs - MODFETs

Schottky diodes. JFETs - MESFETs - MODFETs Technische Universität Graz Institute of Solid State Physics Schottky diodes JFETs - MESFETs - MODFETs Quasi Fermi level When the charge carriers are not in equilibrium the Fermi energy can be different

More information

Peak Electric Field. Junction breakdown occurs when the peak electric field in the PN junction reaches a critical value. For the N + P junction,

Peak Electric Field. Junction breakdown occurs when the peak electric field in the PN junction reaches a critical value. For the N + P junction, Peak Electric Field Junction breakdown occurs when the peak electric field in the P junction reaches a critical value. For the + P junction, qa E ( x) ( xp x), s W dep 2 s ( bi Vr ) 2 s potential barrier

More information

Signal regeneration - optical amplifiers

Signal regeneration - optical amplifiers Signal regeneration - optical amplifiers In any atom or solid, the state of the electrons can change by: 1) Stimulated absorption - in the presence of a light wave, a photon is absorbed, the electron is

More information

CHAPTER 4: P-N P N JUNCTION Part 2. M.N.A. Halif & S.N. Sabki

CHAPTER 4: P-N P N JUNCTION Part 2. M.N.A. Halif & S.N. Sabki CHAPTER 4: P-N P N JUNCTION Part 2 Part 2 Charge Storage & Transient Behavior Junction Breakdown Heterojunction CHARGE STORAGE & TRANSIENT BEHAVIOR Once injected across the junction, the minority carriers

More information

Solid State Physics SEMICONDUCTORS - IV. Lecture 25. A.H. Harker. Physics and Astronomy UCL

Solid State Physics SEMICONDUCTORS - IV. Lecture 25. A.H. Harker. Physics and Astronomy UCL Solid State Physics SEMICONDUCTORS - IV Lecture 25 A.H. Harker Physics and Astronomy UCL 9.9 Carrier diffusion and recombination Suppose we have a p-type semiconductor, i.e. n h >> n e. (1) Create a local

More information

EE 6313 Homework Assignments

EE 6313 Homework Assignments EE 6313 Homework Assignments 1. Homework I: Chapter 1: 1.2, 1.5, 1.7, 1.10, 1.12 [Lattice constant only] (Due Sept. 1, 2009). 2. Homework II: Chapter 1, 2: 1.17, 2.1 (a, c) (k = π/a at zone edge), 2.3

More information

Semiconductor Quantum Structures And Energy Conversion. Itaru Kamiya Toyota Technological Institute

Semiconductor Quantum Structures And Energy Conversion. Itaru Kamiya Toyota Technological Institute Semiconductor Quantum Structures And nergy Conversion April 011, TTI&NCHU Graduate, Special Lectures Itaru Kamiya kamiya@toyota-ti.ac.jp Toyota Technological Institute Outline 1. Introduction. Principle

More information

Hussein Ayedh. PhD Studet Department of Physics

Hussein Ayedh. PhD Studet Department of Physics Hussein Ayedh PhD Studet Department of Physics OUTLINE Introduction Semiconductors Basics DLTS Theory DLTS Requirements Example Summary Introduction Energetically "deep trapping levels in semiconductor

More information

Fundamentals of Photovoltaics: C1 Problems. R.Treharne, K. Durose, J. Major, T. Veal, V.

Fundamentals of Photovoltaics: C1 Problems. R.Treharne, K. Durose, J. Major, T. Veal, V. Fundamentals of Photovoltaics: C1 Problems R.Treharne, K. Durose, J. Major, T. Veal, V. Dhanak @cdtpv November 3, 2015 These problems will be highly relevant to the exam that you will sit very shortly.

More information

Photonics and Optical Communication

Photonics and Optical Communication Photonics and Optical Communication (Course Number 300352) Spring 2007 Optical Source Dr. Dietmar Knipp Assistant Professor of Electrical Engineering http://www.faculty.iu-bremen.de/dknipp/ 1 Photonics

More information

Sheng S. Li. Semiconductor Physical Electronics. Second Edition. With 230 Figures. 4) Springer

Sheng S. Li. Semiconductor Physical Electronics. Second Edition. With 230 Figures. 4) Springer Sheng S. Li Semiconductor Physical Electronics Second Edition With 230 Figures 4) Springer Contents Preface 1. Classification of Solids and Crystal Structure 1 1.1 Introduction 1 1.2 The Bravais Lattice

More information

1 Name: Student number: DEPARTMENT OF PHYSICS AND PHYSICAL OCEANOGRAPHY MEMORIAL UNIVERSITY OF NEWFOUNDLAND. Fall :00-11:00

1 Name: Student number: DEPARTMENT OF PHYSICS AND PHYSICAL OCEANOGRAPHY MEMORIAL UNIVERSITY OF NEWFOUNDLAND. Fall :00-11:00 1 Name: DEPARTMENT OF PHYSICS AND PHYSICAL OCEANOGRAPHY MEMORIAL UNIVERSITY OF NEWFOUNDLAND Final Exam Physics 3000 December 11, 2012 Fall 2012 9:00-11:00 INSTRUCTIONS: 1. Answer all seven (7) questions.

More information

Session 6: Solid State Physics. Diode

Session 6: Solid State Physics. Diode Session 6: Solid State Physics Diode 1 Outline A B C D E F G H I J 2 Definitions / Assumptions Homojunction: the junction is between two regions of the same material Heterojunction: the junction is between

More information

Spring Semester 2012 Final Exam

Spring Semester 2012 Final Exam Spring Semester 2012 Final Exam Note: Show your work, underline results, and always show units. Official exam time: 2.0 hours; an extension of at least 1.0 hour will be granted to anyone. Materials parameters

More information

In a metal, how does the probability distribution of an electron look like at absolute zero?

In a metal, how does the probability distribution of an electron look like at absolute zero? 1 Lecture 6 Laser 2 In a metal, how does the probability distribution of an electron look like at absolute zero? 3 (Atom) Energy Levels For atoms, I draw a lower horizontal to indicate its lowest energy

More information

High Power Diode Lasers

High Power Diode Lasers Lecture 10/1 High Power Diode Lasers Low Power Lasers (below tenth of mw) - Laser as a telecom transmitter; - Laser as a spectroscopic sensor; - Laser as a medical diagnostic tool; - Laser as a write-read

More information

Luminescence basics. Slide # 1

Luminescence basics. Slide # 1 Luminescence basics Types of luminescence Cathodoluminescence: Luminescence due to recombination of EHPs created by energetic electrons. Example: CL mapping system Photoluminescence: Luminescence due to

More information

Light Emitting Diodes

Light Emitting Diodes Light Emitting Diodes WWW.LIGHTEMITTINGDIODES.ORG OPTI 500 A FALL 2012, LECTURE 8 Light Emission from Semiconductor Spontaneous radiative transition in direct bandgap semiconductors generate light ~ E

More information

Current mechanisms Exam January 27, 2012

Current mechanisms Exam January 27, 2012 Current mechanisms Exam January 27, 2012 There are four mechanisms that typically cause currents to flow: thermionic emission, diffusion, drift, and tunneling. Explain briefly which kind of current mechanisms

More information

Emission Spectra of the typical DH laser

Emission Spectra of the typical DH laser Emission Spectra of the typical DH laser Emission spectra of a perfect laser above the threshold, the laser may approach near-perfect monochromatic emission with a spectra width in the order of 1 to 10

More information

FIBER OPTICS. Prof. R.K. Shevgaonkar. Department of Electrical Engineering. Indian Institute of Technology, Bombay. Lecture: 14.

FIBER OPTICS. Prof. R.K. Shevgaonkar. Department of Electrical Engineering. Indian Institute of Technology, Bombay. Lecture: 14. FIBER OPTICS Prof. R.K. Shevgaonkar Department of Electrical Engineering Indian Institute of Technology, Bombay Lecture: 14 Optical Sources Fiber Optics, Prof. R.K. Shevgaonkar, Dept. of Electrical Engineering,

More information

3. Two-dimensional systems

3. Two-dimensional systems 3. Two-dimensional systems Image from IBM-Almaden 1 Introduction Type I: natural layered structures, e.g., graphite (with C nanostructures) Type II: artificial structures, heterojunctions Great technological

More information

PHYSICAL ELECTRONICS(ECE3540) CHAPTER 9 METAL SEMICONDUCTOR AND SEMICONDUCTOR HETERO-JUNCTIONS

PHYSICAL ELECTRONICS(ECE3540) CHAPTER 9 METAL SEMICONDUCTOR AND SEMICONDUCTOR HETERO-JUNCTIONS PHYSICAL ELECTRONICS(ECE3540) CHAPTER 9 METAL SEMICONDUCTOR AND SEMICONDUCTOR HETERO-JUNCTIONS Tennessee Technological University Wednesday, October 30, 013 1 Introduction Chapter 4: we considered the

More information

ELECTRONIC DEVICES AND CIRCUITS SUMMARY

ELECTRONIC DEVICES AND CIRCUITS SUMMARY ELECTRONIC DEVICES AND CIRCUITS SUMMARY Classification of Materials: Insulator: An insulator is a material that offers a very low level (or negligible) of conductivity when voltage is applied. Eg: Paper,

More information

Chapter 7. The pn Junction

Chapter 7. The pn Junction Chapter 7 The pn Junction Chapter 7 PN Junction PN junction can be fabricated by implanting or diffusing donors into a P-type substrate such that a layer of semiconductor is converted into N type. Converting

More information

Effect of non-uniform distribution of electric field on diffusedquantum well lasers

Effect of non-uniform distribution of electric field on diffusedquantum well lasers Title Effect of non-uniform distribution of electric field on diffusedquantum well lasers Author(s) Man, WM; Yu, SF Citation IEEE Hong Kong Electron Devices Meeting Proceedings, Hong Kong, China, 29 August

More information

Thermionic Current Modeling and Equivalent Circuit of a III-V MQW P-I-N Photovoltaic Heterostructure

Thermionic Current Modeling and Equivalent Circuit of a III-V MQW P-I-N Photovoltaic Heterostructure Thermionic Current Modeling and Equivalent Circuit of a III-V MQW P-I-N Photovoltaic Heterostructure ARGYRIOS C. VARONIDES Physics and Electrical Engineering Department University of Scranton 800 Linden

More information

CHAPTER 2 PHYSICS OF LEDS

CHAPTER 2 PHYSICS OF LEDS CHAPTER 2 PHYSICS OF LEDS 2.1 LIGHT EMITTING DIODE A light-emitting diode (LED) is simply a two terminal p-n junction diode, which emits light when forward bias is applied across the terminals. When an

More information

KATIHAL FİZİĞİ MNT-510

KATIHAL FİZİĞİ MNT-510 KATIHAL FİZİĞİ MNT-510 YARIİLETKENLER Kaynaklar: Katıhal Fiziği, Prof. Dr. Mustafa Dikici, Seçkin Yayıncılık Katıhal Fiziği, Şakir Aydoğan, Nobel Yayıncılık, Physics for Computer Science Students: With

More information

Lecture 16 - The pn Junction Diode (II) Equivalent Circuit Model. April 8, 2003

Lecture 16 - The pn Junction Diode (II) Equivalent Circuit Model. April 8, 2003 6.012 - Microelectronic Devices and Circuits - Spring 2003 Lecture 16-1 Lecture 16 - The pn Junction Diode (II) Equivalent Circuit Model April 8, 2003 Contents: 1. I-V characteristics (cont.) 2. Small-signal

More information

Lecture 15 The pn Junction Diode (II)

Lecture 15 The pn Junction Diode (II) Lecture 15 The pn Junction Diode (II I-V characteristics Forward Bias Reverse Bias Outline Reading Assignment: Howe and Sodini; Chapter 6, Sections 6.4-6.5 6.012 Spring 2007 Lecture 15 1 1. I-V Characteristics

More information

Avalanche breakdown. Impact ionization causes an avalanche of current. Occurs at low doping

Avalanche breakdown. Impact ionization causes an avalanche of current. Occurs at low doping Avalanche breakdown Impact ionization causes an avalanche of current Occurs at low doping Zener tunneling Electrons tunnel from valence band to conduction band Occurs at high doping Tunneling wave decays

More information

LEC E T C U T R U E R E 17 -Photodetectors

LEC E T C U T R U E R E 17 -Photodetectors LECTURE 17 -Photodetectors Topics to be covered Photodetectors PIN photodiode Avalanche Photodiode Photodetectors Principle of the p-n junction Photodiode A generic photodiode. Photodetectors Principle

More information

6. Light emitting devices

6. Light emitting devices 6. Light emitting devices 6. The light emitting diode 6.. Introduction A light emitting diode consist of a p-n diode which is designed so that radiative recombination dominates. Homojunction p-n diodes,

More information

EE 5611 Introduction to Microelectronic Technologies Fall Tuesday, September 23, 2014 Lecture 07

EE 5611 Introduction to Microelectronic Technologies Fall Tuesday, September 23, 2014 Lecture 07 EE 5611 Introduction to Microelectronic Technologies Fall 2014 Tuesday, September 23, 2014 Lecture 07 1 Introduction to Solar Cells Topics to be covered: Solar cells and sun light Review on semiconductor

More information

The Law of the Junction Revisited. Mark Lundstrom Network for Computational Nanotechnology and Purdue University ( ). (1)

The Law of the Junction Revisited. Mark Lundstrom Network for Computational Nanotechnology and Purdue University ( ). (1) The Law of the Junction Revisited Mark Lundstrom Network for Computational Nanotechnology and Purdue University Consider a one-sided, short base diode like that shown in Fig.. We usually analyze the I-V

More information

Semiconductor Physics fall 2012 problems

Semiconductor Physics fall 2012 problems Semiconductor Physics fall 2012 problems 1. An n-type sample of silicon has a uniform density N D = 10 16 atoms cm -3 of arsenic, and a p-type silicon sample has N A = 10 15 atoms cm -3 of boron. For each

More information

Photodiodes and other semiconductor devices

Photodiodes and other semiconductor devices Photodiodes and other semiconductor devices Chem 243 Winter 2017 What is a semiconductor? no e - Empty e levels Conduction Band a few e - Empty e levels Filled e levels Filled e levels lots of e - Empty

More information

Course overview. Me: Dr Luke Wilson. The course: Physics and applications of semiconductors. Office: E17 open door policy

Course overview. Me: Dr Luke Wilson. The course: Physics and applications of semiconductors. Office: E17 open door policy Course overview Me: Dr Luke Wilson Office: E17 open door policy email: luke.wilson@sheffield.ac.uk The course: Physics and applications of semiconductors 10 lectures aim is to allow time for at least one

More information

PN Junctions. Lecture 7

PN Junctions. Lecture 7 Lecture 7 PN Junctions Kathy Aidala Applied Physics, G2 Harvard University 10 October, 2002 Wei 1 Active Circuit Elements Why are they desirable? Much greater flexibility in circuit applications. What

More information

Institute of Solid State Physics. Technische Universität Graz. Exam. Feb 2, 10:00-11:00 P2

Institute of Solid State Physics. Technische Universität Graz. Exam. Feb 2, 10:00-11:00 P2 Technische Universität Graz nstitute of Solid State Physics Exam Feb 2, 10:00-11:00 P2 Exam Four questions, two from the online list. Calculator is ok. No notes. Explain some concept: (tunnel contact,

More information

Solar Cell Materials and Device Characterization

Solar Cell Materials and Device Characterization Solar Cell Materials and Device Characterization April 3, 2012 The University of Toledo, Department of Physics and Astronomy SSARE, PVIC Principles and Varieties of Solar Energy (PHYS 4400) and Fundamentals

More information

Lecture 15 - The pn Junction Diode (I) I-V Characteristics. November 1, 2005

Lecture 15 - The pn Junction Diode (I) I-V Characteristics. November 1, 2005 6.012 - Microelectronic Devices and Circuits - Fall 2005 Lecture 15-1 Lecture 15 - The pn Junction Diode (I) I-V Characteristics November 1, 2005 Contents: 1. pn junction under bias 2. I-V characteristics

More information

Lecture 20: Semiconductor Structures Kittel Ch 17, p , extra material in the class notes

Lecture 20: Semiconductor Structures Kittel Ch 17, p , extra material in the class notes Lecture 20: Semiconductor Structures Kittel Ch 17, p 494-503, 507-511 + extra material in the class notes MOS Structure Layer Structure metal Oxide insulator Semiconductor Semiconductor Large-gap Semiconductor

More information

ELE46703 TEST #1 Take-Home Solutions Prof. Guvench...

ELE46703 TEST #1 Take-Home Solutions Prof. Guvench... ELE46703 TEST #1 Take-Home Solutions Prof. Guvench... Problem 1 : Light Emitting Diode (60 pts.) Consider a GaAs pn junction which has the following properties. N a 10 16 cm -3 (p-side), N d 10 19 cm -3

More information

Semiconductor Junctions

Semiconductor Junctions 8 Semiconductor Junctions Almost all solar cells contain junctions between different materials of different doping. Since these junctions are crucial to the operation of the solar cell, we will discuss

More information

FIBER OPTICS. Prof. R.K. Shevgaonkar. Department of Electrical Engineering. Indian Institute of Technology, Bombay. Lecture: 12.

FIBER OPTICS. Prof. R.K. Shevgaonkar. Department of Electrical Engineering. Indian Institute of Technology, Bombay. Lecture: 12. FIBER OPTICS Prof. R.K. Shevgaonkar Department of Electrical Engineering Indian Institute of Technology, Bombay Lecture: 12 Optical Sources Fiber Optics, Prof. R.K. Shevgaonkar, Dept. of Electrical Engineering,

More information

Computer Aided Design of GaN Light-Emitting Diodes. Copyright 2006 Crosslight Software Inc.

Computer Aided Design of GaN Light-Emitting Diodes. Copyright 2006 Crosslight Software Inc. Computer Aided Design of GaN Light-Emitting Diodes Copyright 2006 Crosslight Software Inc. www.crosslight.com 1 2 Contents Available tools and modules. Simulation of IQE droop. Design of superlattice.

More information

EE 130 Intro to MS Junctions Week 6 Notes. What is the work function? Energy to excite electron from Fermi level to the vacuum level

EE 130 Intro to MS Junctions Week 6 Notes. What is the work function? Energy to excite electron from Fermi level to the vacuum level EE 13 Intro to S Junctions eek 6 Notes Problem 1 hat is the work function? Energy to ecite electron from Fermi level to the vacuum level Electron affinity of 4.5eV Electron affinity of Ge 4.eV orkfunction

More information

Chapter 7. Solar Cell

Chapter 7. Solar Cell Chapter 7 Solar Cell 7.0 Introduction Solar cells are useful for both space and terrestrial application. Solar cells furnish the long duration power supply for satellites. It converts sunlight directly

More information

Quantum Phenomena & Nanotechnology (4B5)

Quantum Phenomena & Nanotechnology (4B5) Quantum Phenomena & Nanotechnology (4B5) The 2-dimensional electron gas (2DEG), Resonant Tunneling diodes, Hot electron transistors Lecture 11 In this lecture, we are going to look at 2-dimensional electron

More information

Photonic Devices. Light absorption and emission. Transitions between discrete states

Photonic Devices. Light absorption and emission. Transitions between discrete states Light absorption and emission Photonic Devices Transitions between discrete states Transition rate determined by the two states: Fermi s golden rule Absorption and emission of a semiconductor Vertical

More information

Semiconductor Physics and Devices

Semiconductor Physics and Devices The pn Junction 1) Charge carriers crossing the junction. 3) Barrier potential Semiconductor Physics and Devices Chapter 8. The pn Junction Diode 2) Formation of positive and negative ions. 4) Formation

More information

Nanomaterials for Photovoltaics (v11) 14. Intermediate-Band Solar Cells

Nanomaterials for Photovoltaics (v11) 14. Intermediate-Band Solar Cells 1 14. Intermediate-Band Solar Cells Intermediate (impurity) band solar cells (IBSCs) (I) Concept first proposed by A. Luque and A. Martí in 1997. Establish an additional electronic band within the band

More information

Chapter 3 Properties of Nanostructures

Chapter 3 Properties of Nanostructures Chapter 3 Properties of Nanostructures In Chapter 2, the reduction of the extent of a solid in one or more dimensions was shown to lead to a dramatic alteration of the overall behavior of the solids. Generally,

More information

Schottky Rectifiers Zheng Yang (ERF 3017,

Schottky Rectifiers Zheng Yang (ERF 3017, ECE442 Power Semiconductor Devices and Integrated Circuits Schottky Rectifiers Zheng Yang (ERF 3017, email: yangzhen@uic.edu) Power Schottky Rectifier Structure 2 Metal-Semiconductor Contact The work function

More information

What do we study and do?

What do we study and do? What do we study and do? Light comes from electrons transitioning from higher energy to lower energy levels. Wave-particle nature of light Wave nature: refraction, diffraction, interference (labs) Particle

More information

This is the 15th lecture of this course in which we begin a new topic, Excess Carriers. This topic will be covered in two lectures.

This is the 15th lecture of this course in which we begin a new topic, Excess Carriers. This topic will be covered in two lectures. Solid State Devices Dr. S. Karmalkar Department of Electronics and Communication Engineering Indian Institute of Technology, Madras Lecture - 15 Excess Carriers This is the 15th lecture of this course

More information

Semiconductor. Byungwoo Park. Department of Materials Science and Engineering Seoul National University.

Semiconductor. Byungwoo Park.   Department of Materials Science and Engineering Seoul National University. Semiconductor Byungwoo Park Department of Materials Science and Engineering Seoul National University http://bp.snu.ac.kr http://bp.snu.ac.kr Semiconductors Kittel, Solid State Physics (Chapters 7 and

More information

Chemistry Instrumental Analysis Lecture 8. Chem 4631

Chemistry Instrumental Analysis Lecture 8. Chem 4631 Chemistry 4631 Instrumental Analysis Lecture 8 UV to IR Components of Optical Basic components of spectroscopic instruments: stable source of radiant energy transparent container to hold sample device

More information

* motif: a single or repeated design or color

* motif: a single or repeated design or color Chapter 2. Structure A. Electronic structure vs. Geometric structure B. Clean surface vs. Adsorbate covered surface (substrate + overlayer) C. Adsorbate structure - how are the adsorbed molecules bound

More information

Fundamentals of Semiconductor Physics

Fundamentals of Semiconductor Physics Fall 2007 Fundamentals of Semiconductor Physics 万 歆 Zhejiang Institute of Modern Physics xinwan@zimp.zju.edu.cn http://zimp.zju.edu.cn/~xinwan/ Transistor technology evokes new physics The objective of

More information