ANISOTROPIC MAGNETOTRANSPORT IN 2-DIMENSIONAL ELECTRON GASES ON (311)B GAAS SUBSTRATES

Interest in electron transport on high-index GaAs surfaces is increasi ng, especially since the advent of patterned substrate regrowth, in wh ich high index surfaces are revealed on (001) GaAs after etching. In t his paper we observe anisotropic mobility in orthogonal directions in two-dimensional electron gases grown on (311)B GaAs substrates. The mo bility in the [233BAR] direction is found to be up to 50in the [011BAR ] direction. The lower mobility is accompanied by a large anomalous ne gative magnetoresistance. These effects are studied as a function of t emperature and carrier density. It is suggested that interface roughne ss scattering could be a cause for the large anisotropies in mobility and a simple calculation is performed to demonstrate this hypothesis.