Pressure‐induced transition of 2DEG in δ‐doped GaAs to insulating state

Abstract

AbstractThe tunnelling and lateral conductance of a two‐dimensional electron gas (2DEG) formed in GaAs with a δ‐doped layer were measured simultaneously at hydrostatic pressures at helium temperatures. The resistivity of the δ‐doped layer sharply increases by more than three orders of magnitude at about 2 GPa and its temperature coefficient changes from about –0.04 to about –4 K–1. The tunnelling resistance shows only a slight change of exponential behaviour at about 1.5 GPa while a drastic change of the zero bias anomaly (ZBA) takes place just at the metal–insulator transition (MIT). Such behaviour is interpreted in terms of the pressure dependence of the GaAs band structure and DX‐level position as well as Coulomb gap formation at the MIT. (© 2007 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)