Conductance anisotropy of high-mobility two-dimensional hole gas at GaAs/(Al,Ga)As(1 1 3)A single heterojunctions

We investigate the anisotropy of mobility of two-dimensional hole gases formed at modulation-doped single GaAs/(Al,Ga)As heterojunctions on GaAs(113)A in dependence on the surface morphology arising during molecular-beam epitaxy growth. A regular step distribution along the [View the MathML source] direction results in nearly two times higher mobility compared to the [View the MathML source 1 0] direction. The magnetoresistance at low magnetic fields exhibits features, which allow to determine an effective electronic correlation length for hole scattering which correlates with the step distribution obtained from AFM images. This correlation length governs the mobility anisotropy. In addition, we estimate the amplitude of the potential modulation by means of the low-field positive magnetoresistance in high-mobility two-dimensional hole gases.