High‐field thermal noise of holes in silicon: The effect of valence band anisotropy

Abstract

The effects of valence band anisotropy on longitudinal and transverse high‐field differential mobilities, diffusivities, and thermal noise temperatures were theoretically investigated. The effects were examined for holes in silicon and in several hypothetical materials having systematically varied degrees of valence band anisotropy. The results show a pronounced dependence of the transverse high‐field differential mobility and of the longitudinal high‐field noise temperature upon the degree of anisotropy. This suggests that thermal noise measurements may provide an alternative to magnetotransport methods as a valence bandstructure measurement technique. The results also imply that thermal noise in semiconductor devices can be mitigated by choosing a semiconductor with a low degree of valence band anisotropy and, for a given semiconductor, by properly aligning the device layout with respect to the material crystallographic axes. © 1996 American Institute of Physics.