Interface structure of hydride vapor phase epitaxial GaN grown with high-temperature reactively sputtered AlN buffer

Thick hydride vapor phase epitaxy GaN layers have been grown on a-plane sap phire using high-temperature ion-assisted reactively sputtered AlN as a buf fer layer. Transmission electron microscopy and atomic force microscopy wer e carried out to study the formation of the two interfaces sapphire/AlN and AlN/GaN, and their influence on the microstructure of both the buffer laye r and the main GaN layer. It was demonstrated that the high-temperature rea ctively sputtered buffer layer provides a good alternative for hydride vapo r phase epitaxy growth of GaN layers. In particular, the buffer promotes a specific interface ordering mechanism different from that observed on low-t emperature buffers. (C) 2000 American Institute of Physics. [S0003-6951(00) 00314-4].