Properties of hot photoexcited holes in Cu-doped germanium at low temperature

Abstract

A theoretical study is made of the properties of hot photoexcited holes in Cu-doped Germanium as a function of the lattice temperature and compensation density ( N d ). Numerical solutions of the rate equation, obtained by an iterative technique, give the steady-state energy distribution of hot photoexcited holes due to aproximately blackbody room temperature radiation. Considering only a spherical heavy-hole band, simple acoustic deformation scattering and instantaneous optical phonon emission it is found that for the lowest values of N d the energy distribution function is approximately Maxwellian and gives a good fit with experimental photohall mobilities. For higher values of N d , a spherical light hole band is included in the calculations and this involves the use of a two-parameter deformation potential for inter- and intra-valley transverse and longitudinal scattering, and also instantaneous inter- and intra-valley optical scattering. The experimental photohall mobilities can then be used to give information on the deformation potential parameters for the valence band of Ge which cannot be derived from equilibrium transport measurements.