Suppression of deformation-potential electron-acoustic-phonon coupling in Si delta -doped GaAs structures.

Abstract

We have used the heat-pulse technique to investigate phonon emission from two-dimensional electron gases formed in a series of molecular-beam-epitaxy- and metal-organic chemical-vapor-deposition-grown Si \ensuremath{\delta}-doped GaAs structures with single subband occupation. By comparing the relative intensities of longitudinal and transverse acoustic-phonon emission over a wide range of input powers (0.01--1000 pW per electron) we suggest that deformation-potential coupling to longitudinal modes is suppressed in the acoustic regime (${\mathit{T}}_{\mathit{e}}$50 K). In all samples the onset of optical-phonon emission was at input powers around 1.5 pW per electron, a value similar to that found in the heterojunction and quantum-well cases. Strong LA-mode emission is observed at all powers in contrast to previous observations in the heterojunction system.