Highly anisotropic electron mobilities of GaAs/In0.2Ga0.8As/Al0.3Ga0.7As inverted high electron mobility transistor structures

Abstract

Anisotropic electron mobilities for GaAs/In_0.2Ga_0.8As/Al_0.3Ga_0.7As inverted high electron mobility transistor structures were observed using Hall effect measurements. If the In_0.2Ga_0.8As quantum‐well thickness is below the critical layer thickness, a higher electron mobility in the 〈01–1〉 direction is observed in comparison to the 〈011〉 direction. Exceeding the critical layer thickness of the In_0.2Ga_0.8As quantum well results in a change in the behavior of the anisotropy, and a highly anisotropic electron mobility with a higher electron mobility in the 〈011〉 direction, in comparison to the 〈01–1〉 direction, is observed. With increasing In_0.2Ga_0.8As quantum‐well width, the anisotropy increases. An increase of the anisotropy was also observed if the Hall‐effect measurements were carried out at lower temperatures. The anisotropy in the electron mobility can be correlated to the occurrence of a highly asymmetric‐dislocation density. The asymmetry in the dislocation density was observed using wavelength‐selective catholuminescence measurements.