Study of the effects of an AlN interlayer on the transport properties of AlGaN∕AlN∕GaN heterostructures grown on SiC

Abstract

Transport measurements were used to characterize AlGaN∕AlN∕GaN∕SiC. While the carrier concentration, n=9.2×1012cm−2, remained relatively unchanged from 300 down to 1.2K, the mobility increased from 2100 to over 3×104cm2∕Vs. Shubnikov-de Haas oscillations were observed in fields as low as 2T. Despite the high n, quantum Hall plateaus, which are rarely reported in conventional AlGaN∕GaN with comparable n, were observed. The calculated quantum scattering time of 0.28ps is longer than what is typically reported for conventional AlGaN∕GaN. This improvement is believed to be due to a reduction in alloy scattering.