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2019/20 Undergraduate Module Catalogue

ELEC2240 Transistors and Optoelectronic Devices

20 creditsClass Size: 100

Module manager: Prof A G Davies
Email: g.davies@leeds.ac.uk

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

Year running 2019/20

This module is not approved as a discovery module

Objectives

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 the operation of the p-n junction diode, and be able to analyse its properties using its bandstructure.
2. Explain the operation of light emitting diode, and how they are fabricated.
3. Understand the basic operation of a laser, the concept of population inversion, and how a laser fundamentally operates differently from a LED.
4. Understand the importance of bandstructure in the design and operation of a range of electronic and optoelectronic devices, and appreciate the role of quantum mechanics in underpinning a material's bandstructure.
5. Explain how a two-dimensional electron system can be formed in silicon MOSFETs and in GaAs-AlGaAs heterojunctions, the concept of field effect, and how these devices can show transistor action.
6. Understand the basic operation principles of photodiodes as photodetectors and the factors influencing their efficiency and responsivity.
7. Understand the use of p-n junctions in different configurations as photovoltaic devices, and the characteristics of solar cells made of different materials.
8. Understand the operation of the bipolar junction transistor, and be able to utilize its properties in different applications.


Syllabus

1. Revision of bandstructures for metals and semiconductors, doping, n- and p-type semiconductors, Fermi energy, law of mass action.
2. Revision of p-n junction diodes. Depletion region, built-in potential. Behaviour of diode as a function of forward and reverse bias in terms of bandstructure. Derive Shockley diode equation.
3. The light emitting diode (LED). Homojunction and double-heterojunction LEDs. Overview of molecular beam epitaxy as a method to fabricate layered semiconductor devices.
4. Elementary quantum mechanics. Light as a wave, the electron as a wave. The infinite potential well (particle-in-the-box), subbands, quantized energies, the electron wave function.
5. Energy levels in atoms, molecules, and crystalline materials. Origin of energy bands. Dispersion curves. Effective mass. Bloch electron waves.
6. Return to LEDs. Comparison of direct/indirect bandgap semiconductors. Emission spectrum and characteristics of red LED.
7. Spontaneous vs stimulated emission. Population inversion. The LASER. Comparison of the ruby laser, the erbium-doped fibre laser, the He-Ne gas laser. Gain curve, laser cavity, Fabry-Pérot modes.
8. The pn-junction diode laser, homojunction and heterojunction devices. Quantum-confined semiconductor lasers. The quantum cascade laser.
9. The bipolar transistor in common base and common emitter configurations and their application as amplifiers.
10. The junction field effect transistor (JFET) and the MOSFET and their use as amplifiers.
11. The principle of the p-n junction photodiode, Ramo’s theorem and external photocurrent. Absorption coefficient and photodiode materials (indirect vs indirect band gap). Quantum efficiency and responsivity. The pin photodiode and the avalanche photodiode.
12. The solar energy spectrum. Photovoltaic device principles. p-n junction photovoltaic I-V characteristics. Solar cells materials, devices and efficiencies.

Teaching methods

Delivery typeNumberLength hoursStudent hours
Example Class201.0020.00
Class tests, exams and assessment12.002.00
Lecture401.0040.00
Private study hours138.00
Total Contact hours62.00
Total hours (100hr per 10 credits)200.00

Private study

80 hours reading before and after lectures (2 hours per lecture);
32 hours preparing and practising numerical examples for Examples Classes;
25 hours revision.

Opportunities for Formative Feedback

Student progress will be monitored at Examples Classes. The mid-sessional test will give quantitative feedback on student progress.

Methods of assessment


Coursework
Assessment typeNotes% of formal assessment
In-course AssessmentSemester 1 (End) Test20.00
Problem SheetProblem Sheet 110.00
Problem SheetProblem Sheet 210.00
Total percentage (Assessment Coursework)40.00

.


Exams
Exam typeExam duration% of formal assessment
Standard exam (closed essays, MCQs etc)2 hr 60.00
Total percentage (Assessment Exams)60.00

Re-sits for ELEC modules are subject to the rules in the School’s Code of Practice on Assessment. Students should be aware that, for some modules, a re-sit may only be conducted on an internal basis (with tuition) in the next academic session.

Reading list

There is no reading list for this module

Last updated: 30/04/2019

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