Department of Physics, Unit Catalogue 2006/07

PH30033 Low-dimensional semiconductors

Credits: 6

Level: Honours

Semester: 2

Assessment: EX80CW20

Requisites:

Before taking this unit you must take PH20013 and take PH20015 and take PH20017 and take PH30023

Aims & Learning Objectives:
The aims of this unit are to give an introduction to the semiconductor physics relating to a range of advanced electronic and optoelectronic devices and to develop an understanding of how fundamental principles affect device performance. After taking this unit the student should be able to:
* explain the concept of bandgap engineering and draw energy band diagrams of undoped and doped semiconductor heterostructures;
* discuss the main properties of semiconductor quantum wells, superlattices and quantum dots and their uses in electronic and optoelectronic devices;
* outline the origin of tunnelling and resonant tunnelling and explain the operation of the resonant tunnelling diode;
* describe the interactions between electrons and photons such as absorption, spontaneous emission and stimulated emission;
* give examples of common optoelectronic devices for emitting, detecting and modulating light, and explain their physical principles of operation;
* distinguish between the optoelectronic properties of bulk and quantum well semiconductors.
Content:
Semiconductor heterostructures: Alloys, Vegard's law, bandgap engineering, band offsets. Semiconductor quantum wells: energy levels, density of states, occupation of subbands. Superlattices, tunnelling barriers, resonant tunnelling. Quantum wires and quantum dots. Strained systems: atomic structure, critical interface, effects of strain on bulk bandstructures. Electronic properties and devices: Tunnelling barriers, transmission coefficient, current and conductance. Resonant tunnelling, resonant tunnelling diode. Doped heterostructure: band bending at interfaces, modulation doping, construction of band diagrams, MODFET. Optoelectronic properties and devices: Electron-photon interaction in semiconductors. Optical absorption in bulk semiconductors: spectral dependence, photocurrent, P-I-N photodiodes, avalanche detectors, solar cells. Optical absorption in quantum wells: interband and intersubband transitions, selection rules. Excitons in bulk semiconductors and quantum wells. Quantum-confined Stark effect and quantum well modulators. Optical emission in semiconductors: radiative and non-radiative transitions, light-emitting diodes, optical gain in bulk and quantum well semiconductors, semiconductor optical amplifiers, bulk and quantum well semiconductor lasers. Advanced semiconductor lasers: distributed feedback lasers, vertical cavity surface emitting lasers, quantum cascade lasers.

University | Catalogues for 2006/07