Electron Transport in Antidot GaAs/AlGaAs Structures under Hydrostatic Pressure

Abstract

On GaAs/AlGaAs heterostructures, the magnetotransport of a two dimensional electron gas in a modulated potential is investigated as a function of hydrostatic pressure and gate voltage. In the transition region between a lateral surface superlattice and an antidot structure, both gate voltage and hydrostatic pressure was used to change the electron density. The application of pressure leads to significant changes in the occupation of donor states in the AlGaAs barrier. As a result, the potential modulation is decreased. Above a critical pressure, where the Fermi level becomes lower than the potential modulation, the formation of antidots is evident as a sudden decrease of the electron mobility. In antidot regime, the change of the mobility as a function of the electron density is much weaker in pressurized systems than in comparable gated structures. This effect is consistently explained by the screening of scattering centers due to the pressure induced formation of dipoles consisting of positive and negative donors inside the AlGaAs barrier.