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2021/22 Undergraduate Module Catalogue

XJEL2240 Transistors and Optoelectronic Devices

20 creditsClass Size: 60

Module manager: Dr. Alex Valavanis

Taught: Semesters 1 & 2 (Sep to Jun) View Timetable

Year running 2021/22

This module is not approved as a discovery module

Module summary

The teaching and assessment methods shown below will be kept under review during 2021-22. If it is not possible to deliver traditional teaching methods, such as lectures and practical classes, we may need to substitute alternative (online) formats of delivery and amend the timetable accordingly. ‘Independent online learning’ may involve watching pre-recorded lecture material or screen-casts, engaging in learning activities such as online worked examples or mini-projects, etc. Students will be expected to fully engage with all of these activities. The time commitment for independent online learning, and also the frequency and duration of online sessions are approximate and intended as a guide only. Further details will be confirmed when the module commences.Where assessments are shown as Online Time-Limited Assessments, the durations shown are indicative only. The actual time permitted for individual assessments will be confirmed prior to the assessments taking place.


The aim of this module is to give students specialist knowledge and understanding of the properties of the semiconductor materials and devices used for transistors and optoelectronic devices. Students will gain an understanding of the principles of semiconductor physics, including an introduction to quantum mechanics and the design and analysis of important representative devices.

Learning outcomes
On completion of this module students should be able to:

1. Explain and analyse the role of bandstructure in the operation of p-n junction diodes.
2. Evaluate and discuss the distribution of charge carriers, and the current–voltage relationship in p-n junction diode.
3. Explain the operating principles of light emitting diodes (LEDs) and lasers, and how these devices operate in a fundamentally different manner.
4. Design and analyse LEDs and lasers, using the principles of quantum mechanics, bandstructure and waveguide theory.
5. Explain the operating principles of photodiodes as photodetectors and evaluate their efficiency and responsivity.
6. Explain the use of p-n junctions as photovoltaic devices and evaluate the characteristics of solar cells made of different materials.
7. Explain the operation of bipolar junction transistors (BJTs), metal-oxide-semiconductor field-effect transistors (MOSFETs) and junction-field effect transistors (JFETs) in terms of their I-V characteristics, analysed from a microscopic point of view.
8. Design and evaluate the operation of simple transistor amplifier circuits, using BJTs, MOSFETs and JFETs.


Topics may include, but are not limited to:

UNIT 1: Semiconductors and diodes
Band structure and conduction in metals and semiconductors, Fermi energy, electrons and holes
Doping in semiconductors (n-type and p-type)
The Fermi–Dirac distribution, density of states and carrier density, law of mass action
The p–n junction, drift and diffusion currents, energy bands, charge distribution and built-in potential
The Shockley diode equation, capacitance in p–n junctions

UNIT 2: Light-emitting diodes and lasers
Light-emitting diodes (LEDs), compound semiconductors, molecular-beam epitaxy, and double-heterojunction LEDs
Introduction to quantum mechanics, the Schroedinger equation and dispersion curves, effective mass, direct and indirect bandgap semiconductors
Lasers and stimulated emission, practical laser devices and Fabry-Pérot cavities, p–n junction laser diodes, double heterojunction laser
Quantum wells and the quantum-well laser, quantum cascade lasers, and applications of terahertz radiation

UNIT 3: Photodiodes and Photovoltaics
Photodiodes, absorption coefficient and photodiode materials (indirect vs indirect band gap)
The p-n junction photodiode, Ramo’s theorem and external photocurrent, quantum efficiency and responsivity, pin photodiodes, avalanche photodiodes
Phototransistors and photoconductive detectors, noise in photodetectors, the solar energy spectrum
Photovoltaic device principles, p-n junction photovoltaic I-V characteristics, equivalent circuits and temperature effects, solar cells materials, devices and efficiencies

UNIT 4: Transistors
The bipolar junction transistor, common-base configuration and common-base and common-emitter amplifiers
The junction field-effect transistor (JFET), operation under negative gate–source bias and JFET amplifier circuits
Metal-oxide-semiconductor field-effect transistors (MOSFETs), enhancement-mode MOSFETs and threshold voltage in MOSFETs

Teaching methods

Delivery typeNumberLength hoursStudent hours
Example Class201.0020.00
Private study hours140.00
Total Contact hours60.00
Total hours (100hr per 10 credits)200.00

Private study

Students are expected to use private study time to consolidate their understanding of course materials, to undertake preparatory work for seminars, workshops, tutorials, examples classes and practical classes, and also to prepare for in-course and summative assessments.

Opportunities for Formative Feedback

Students studying ELEC modules will receive formative feedback in a variety of ways, including the use of self-test quizzes on Minerva, practice questions/worked examples and (where appropriate) through verbal interaction with teaching staff and/or post-graduate demonstrators.

Methods of assessment

Assessment typeNotes% of formal assessment
Online AssessmentOnline Assessment 130.00
Online AssessmentOnline Assessment 230.00
In-course AssessmentRevision Tests20.00
In-course AssessmentUnit Assignments20.00
Total percentage (Assessment Coursework)100.00

Resits for ELEC and XJEL modules are subject to the School's Resit Policy and the Code of Practice on Assessment (CoPA), which are available on Minerva. Students should be aware that, for some modules, a resit may only be conducted on an internal basis (with tuition) in the next academic session.

Reading list

The reading list is available from the Library website

Last updated: 21/09/2021 10:13:37


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