Fundamental Properties of Semiconductors Research Centre

Staff: Professor Peter Fisher, Dr Carey Freeth, Dr Roger Lewis, Dr David Martin, Dr Phil Simmonds, Mr George Takacs, Dr Rodney Vickers, Dr Chao Zhang

Electrical Characterisation of Low Dimension Structures

A novel technique has been developed to probe the electrical characteristics of resonance due to electron tunnelling through barriers in layered semiconductor structures. The measurements reveal the details of multistable regions and are coupled with spectroscopic techniques (see below) to give a description of the physical processes involved in the tunnelling.

Optical Spectroscopy of Semiconductors

Optical spectroscopy is used in the study of the electronic states in elemental and compound semiconductors. Absorption, photoluminescence and Raman spectroscopy utilise optically pumped Far-infrared laser state-of-the-art, very high resolution, Fourier and grating spectrometers; 25 watt Ar+ laser; dye and titanium-sapphire lasers; and a high field superconducting magnet. Elementary excitations and impurities in semiconductors are the main areas of interest. The materials include the new and technologically important quantum well semiconductor structures. Under study are acceptor and band states in bulk GaAs, Ge and Si and in quantum wells and heterostructures. Externally applied magnetic fields and/or uniaxial stresses produce very rich and detailed spectra. Theoretical support is provided for all areas of this research.

Theoretical Solid State Physics

The optical properties and transport phenomena of solids, especially semiconductors, are being studied, along with superconductors and other many-electron systems. Research in this field is carried out using techniques of many-body theory, quantum dynamics, kinetic theorem, band calculations and computer simulations.
Recent projects include: phonon and impurity related optical absorption in III-V semiconductors, in particular, the effects of magnetic field and stress; quantum tunnelling, magnetotransport and quantum interference effects in microstructures; exchange and correlation effects in many-electron system under strong magnetic fields and at low temperature; cyclotron resonance and magneto-optics in extreme quantum limit.