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 epitaxy using RF-plasma nitrogen on (0001) Al2O3 substrates were remarkably improved by introduction of high-temperature grown AlN multiple intermediate layers (HT-AlN-MILs). The effects of HT-AlN-MIL on the improvement of crystal 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 improved the surface morphology. The combination of 8 nm- and 2 nm-thick HT-AlN-MILs brought about improvement of both electrical property and surface morphology, concurrently. The HT-AlN-MIL was used for RF-MBE re-growth on MOCVD-GaN template. Relatively tine step flow structure without spiral hillocks was obtained. (C) 2001 Elsevier Science B.V. All rights reserved.