GaN/AlGaN two-dimensional electron gas grown by ammonia-MBE on MOCVD GaN template

The growth of high quality GaN/AlGaN two-dimensional electron gas on MOCVD GaN template substrates by ammonia-MBE is reported. The homoepitaxial growth required a significantly lower growth temperature than that needed for growth on SiC or sapphire substrates, and yielded significantly improved surface smoothness, and consequently improved electrical, characteristics of the two-dimensional electron gas. A low temperature Hall mobility of 14300 cm²/V s and quantum moblity of 2000 cm²/V s were obtained, representing the highest values observed in the GaN/AlGaN structures grown by the ammonia-MBE technique. A correlation between the surface roughness and increased Hall mobility to quantum mobility ratio was observed, suggesting that the surface roughness could be a source of small-angle scattering in these structures.