Improvement of electrical property and surface morphology of GaN grown by RF-plasma assisted molecular beam epitaxy by introduction of multiple AlN intermediate layer

The crystal properties of Ga-polarity GaN layers grown by molecular beam ep itaxy using RF-plasma nitrogen on (0001) Al2O3 substrates were remarkably i mproved by introduction of high-temperature grown AlN multiple intermediate layers (HT-AlN-MILs). The effects of HT-AlN-MIL on the improvement of crys tal quality were found to be different for its thickness. The 8 nm-thick HT -AlN-MIL improved the electrical property and the 2 nm-thick HT-AlN-MIL imp roved the surface morphology. The combination of 8 nm- and 2 nm-thick HT-Al N-MILs brought about improvement of both electrical property and surface mo rphology, concurrently. The HT-AlN-MIL was used for RF-MBE re-growth on MOC VD-GaN template. Relatively tine step flow structure without spiral hillock s was obtained. (C) 2001 Elsevier Science B.V. All rights reserved.