Cyclotron phonon emission and electron energy loss rates in GaAsGaAlAs heterojunctions

Abstract

Electron energy loss rates have been studied from the amplitude of Shubnikov-deHaas oscillations in GaAsGaAlAs heterojunctions at temperatures between 500mK and 10K. At small magnetic fields there is a considerable enhancement of the loss rate which we interpret as evidence for ‘cyclotron phonon’ emission. When this mechanism is not dominating, we deduce an inelastic electron-acoustic phonon scattering rate of 3 × 10 8 T s −1 K −1. In multi-subband samples the total conductivity is found to depend on the sum of the densities of states in each subband at low temperatures, but at higher electron temperatures is dominated by products of the DOS. This is interpreted in terms of a dominant, acoustic phonon mediated, inter-subband scattering mechanism.