Diffusion thermopower of a $p-$type Si/Si$_{1-x}$Ge$_x$ heterostructure at zero magnetic field

TL;DR

This paper calculates the diffusion thermopower of a degenerate two-dimensional hole gas in a p-type Si/SiGe heterostructure at low temperatures, examining various scattering effects and predicting a sign change in thermopower with layer thickness.

Contribution

It introduces a detailed calculation of diffusion thermopower considering multiple scattering mechanisms and predicts a novel sign change phenomenon based on layer thickness.

Findings

Calculated thermopower fits experimental data

Identified impact of scattering mechanisms on thermopower

Predicted sign change of thermopower with SiGe layer thickness

Abstract

We calculate the diffusion thermopower of the degenerate two-dimensional hole gas in a $p-$type Si/Si$_{1-x}$Ge$_x$ lattice mismatched heterostructure at low temperatures and zero magnetic field. The effects of possible scatterings, e.g. remote impurity, alloy disorder, interface roughness, deformation potential, and random piezoelectric on the hole mobility and the diffusion thermopower are examined. Calculated results are well fitted to the experimental data recently reported. In addition, we predict a possibility for the diffusion thermopower to change its sign as the SiGe layer thickness changes, the effect has not been discussed yet.