Wide temperature range thermopower in GaAs/AlGaAs heterojunctions

Abstract

A systematic analysis of wide-temperature-range (2<T<200 K) thermopower (TP) data, on two-dimensional electron gas at GaAs/AlGaAs heterojunction (HJ) samples of Fletcher et al. [Phys. Rev.B, 50, 14991 (1994)] and Cyca et al. [J. Phys. Condens. Mat, 4, 4491 (1992)], is presented. Numerical results of TP are presented including the contributions from both diffusion TP, Sg and phonon drag TP, Sg. The phonons are considered to be scattered not only by sample boundaries, as assumed in literature, but also by impurities and other phonons. A good representation of the temperature dependence of TP, in all samples considered, is obtained. The parameters characterizing the intrinsic phonon scattering mechanisms are obtained from fitting thermal conductivity data, using modified Callaway model through linear regression method. The study provides a means of assessing the relative importance of carrier scattering mechanisms operative in GaAs HJs. © 2009 American Institute of Physics.