SOME TRANSPORT PROPERTIES OF GaAs/A UNDER TEMPERATURE AND PRESSURE

Abstract

Semiconductors show unusual behaviour under high pressure-from which a wealth of data can be obtained about their structure, optical and electronic properties. Hall Effect measurements to such pressures have produced quite reliable experimental data on the properties of higher-lying band structures. In •this thesis, simulation of the high hydrostatic pressure [OKbar<_P<_6OKbar] effects on the structure, Hall Effect experiment and Resistivity of a GaAs sample having compensated Shallow and Deep Donor. Levels has been carried out. GaAs and AlAs mixed crystals offer the possibilities of their potential applications in various modern optical, electrical and. microwave heterostructure devices. The electrical properties of Ga1_XAIxAs alloys, which have x values near to the direct-indirect conduction band transition composition, are strongly controlled by the emergence of deep levels known as - SDD levels. These deep levels play an important role in limiting the performance of the semiconductor devices. The activation energy of these deep levels and the position of the- subsidiary conduction band can be determined from the temperature dependence [20°K<Ts500°K] of the Hall Effect experiments on these crystals. This thesis also includes simulated plots of the temperature and - pressure dependency of Hall Effect measurements and Resistivity. It is proposed that the properties- of ternary alloys can be provided without having access to these alloys, by using pressure as a tool on a binary system.