ABSTRACT
The study of the crystal structure of group IV and III–V compound materials at pressure have made tremendous advances, both theoretically and experimentally. Structurally, most semiconductors consist of a network of covalent bonds leading to an open crystal structure which, like water, becomes denser on melting. Typically the low- and high-pressure phases are crystallographically simple, while the intermediate ones are complex. Experimentally, high-pressure studies are often confronted with practical difficulties which substantially complicate measurements. These arise from the fact that high pressure can typically be generated only in relatively small sample volumes within a container which will reduce the signal to be measured, while simultaneously contributing strongly to the background noise. Measurement of hardness and resistivity during indentation testing of silicon suggests that a metal-semiconductor phase transformation may be induced by uniaxial strain. The crystallography of the high-pressure phases of tetravalent semiconductors is largely complete, and an extremely reliable theoretical framework for describing structural energies is in place.
