Transport relaxation rate of a two-dimensional electron gas: Surface acoustic-phonon contribution

TL;DR

This paper calculates the transport relaxation rate of a 2D electron gas due to surface acoustic phonons, revealing temperature-dependent behaviors and effects of electron-phonon interactions, with implications for understanding electron mobility at different temperatures.

Contribution

It provides a detailed calculation of the surface acoustic phonon contribution to electron relaxation rates, including temperature dependence and surface effects, which was not thoroughly analyzed before.

Findings

1/tau is linear in T at high temperatures.

Below the Bloch-Gruneisen temperature, 1/tau decreases as T^alpha, with alpha=7 for deformation-potential and 5 for piezoelectric interactions.

Finite distance between surface and electron gas affects relaxation rates.

Abstract

The transport relaxation rate 1/tau of a two-dimensional electron gas due to scattering by thermally excited surface acoustic phonons is calculated. The temperature dependence of 1/tau is found to be linear in T for high temperatures, but decreases like T^alpha as T drops below the Bloch-Gruneisen temperature for surface sound; alpha=7 (5) for the deformation-potential (piezoelectric) interaction. The effect of a finite distance between the crystal surface and the two-dimensional electron gas is discussed. The results are compared with those that have been calculated for three- and two-dimensional phonons interacting with a two-dimensional electron gas.