The growth and physics of high mobility two-dimensional hole gases

Abstract Modulation-doped p-type GaAs-Al x Ga 1−x As heterojunctions have been grown by molecular beam epitaxy (MBE) on the (311)A GaAs surface using silicon as the acceptor. Two-dimensional hole gases with mobilities as high as 570,000 cm 2 V −1 s −1 at 50 mK have been obtained. It is shown that the sample mobility is dependent upon the direction of orientation of the fabricated Hall bar on the MBE wafer which could be due to the anisotropic nature of the Fermi surface in p-type systems. Experimental results on the fractional quantum Hall effect (FQHE) in these high mobility hole gases are also presented.