Al diffusion in GaN buffer layer during the growth of GaN film

The structure, composition and chemical bonding state of the buffer layer produced during the growth of GaN single crystal film were studied by using analytical electron microscopy. It was found that the buffer layer is a compound containing both GaN and AIN (or AlxGa1-xN) although Al was not introduced during the crystal growth. This result indicates that aluminum had diffused from Al2O3 substrate to the buffer layer and some AlN or AlxGa1-xN microcrystals had been formed in the buffer layer. These microcrystals are very important for releasing the stress near the interface. (C) 1999 Published by Elsevier Science B.V. All rights reserved.