THE EFFECT OF BURIED ALXGA1-XN ISOLATING LAYERS ON THE TRANSPORT-PROPERTIES OF GAN DEPOSITED ON SAPPHIRE SUBSTRATE BY MOLECULAR-BEAM EPITAXY USING NH3

It is believed that the highly dislocated region near the GaN/sapphire interface is a degenerate layer. In this paper a direct evidence for such a proposal is presented. By inserting a buried AlxGa1-xN (x > 0.5 ) isolating layer to separate the interface region from the bulk regio n, the background electron concentration can be significantly reduced, while care must be taken to guarantee that there is no degrading of H all mobility when choosing the thickness of the isolating layer. (C) 1 998 Elsevier Science B.V. All rights reserved.