The investigation of the high frequency hopping conductivity in two- and three-dimensional electron gas by an acoustic method

TL;DR

This study investigates high-frequency conductivity in GaAs/AlGaAs heterostructures using acoustic methods, revealing contributions from 2D electrons and hopping conductivity in doped layers, with analysis of temperature dependence and Landau level broadening.

Contribution

It introduces an acoustic method to measure high-frequency conductivity in 2D and 3D electron gases, distinguishing different conduction mechanisms in quantum Hall regimes.

Findings

HF conductivity is influenced by 2D electron and hopping conductivities.

Temperature affects the conductivity components.

Landau level broadening is quantified.

Abstract

High-frequency (HF) conductivity ($\sigma_{hf}$) measured by an acoustical method has been studied in GaAs/AlGaAs heterostructures in a linear and nonlinear regime on acoustic power. It has been shown that in the quantum Hall regime at magnetic fields corresponding to the middle of the Hall plateaus the HF conductivity is determined by the sum of the conductivity of 2-dimensional electrons in the high-mobility channel and the hopping conductivity of the electrons in the doped thick AlGaAs layer. The dependence of these conductivities on a temperature is analyzed. The width of the Landau level broadened by the impurity random potential is determined.