Phonoconductivity measurement of the phonon absorption by a two-dimensional hole gas in a GaAs heterojunction.

Abstract

In this paper we describe measurements of the absorption of acoustic phonons from a ballistic heat pulse by a two-dimensional (2D) hole gas in a GaAs/${\mathrm{Al}}_{\mathit{x}}$${\mathrm{Ga}}_{1\mathrm{\ensuremath{-}}\mathit{x}}$As heterojunction. The phonoconductivity technique was used, in which the change in the resistance of a device caused by phonon absorption is detected. Direct information regarding the hole-phonon interaction in a heterojunction is obtained by this method. Measurements of the phonoconductivity in zero and quantizing magnetic fields were made and compared with the results of numerical calculations of the absorption. In spite of the complicated nature of the 2D hole subbands and the hole-phonon coupling, we find that, at the hole densities and temperatures of these experiments, the theory describing the interaction of 2D electrons with phonons can be reasonably applied to 2D holes with the appropriate change of the effective mass and other relevant parameters, and the use of a single effective valence-band deformation potential. Using our results, we are able to determine the Fang-Howard parameter for the confined holes and the effective mass for heavy holes in the spin-split lowest subband. \textcopyright{} 1996 The American Physical Society.