The Effect of Strain on the Thermoelectric Properties of a Many-Valley Semiconductor

Abstract

The electrical conductivity and thermoelectric power of a many-valley semiconductor are considered as functions of strain, neglecting all effects other than those due to carrier transfer between valleys. For non-degenerate materials, a general treatment is given and it is shown that the absence of other effects can be checked by the condition that the trace of the conductivity tensor is unaltered by the strain. Under these conditions the conductivity and thermoelectric power tensors can be combined to give an expression, valid fur any strain, which according to the theory, involves only the relative shifts in the minimum energies of the valleys. By measuring these for different strains it is possible in principle to obtain the complete deformation potential tensor for a given material. An estimate of the order of magnitude shows that the effects should be readily measurable in n-type germanium.