Department of Physics, Unit Catalogue 2008/09 |
PH30088 Electron transport in low-dimensional semiconductors |
| Credits: 3 |
| Level: Honours |
| Semester: 2 |
| Assessment: |
| Requisites: |
| Before taking this unit you must take PH20013 and take PH20015 and take PH20017 |
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Aims: The aim of this unit is to introduce the physics of semiconductor heterostructures, focussing particularly on electron transport within such structures. A further aim is to develop an understanding of how these fundamental principles affect the performance of some advanced electronic devices.
Learning Outcomes: 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 and superlattices, and their uses in electronic devices; * outline the origin of tunnelling and resonant tunnelling and explain the operation of the resonant tunnelling diode. Skills: Numeracy T/F A, Problem Solving T/F A. 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. 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. Heterojunction Bipolar Transistor. |