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

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.