High-quality AlN grown on Si(111) by gas-source molecular-beam epitaxy with ammonia

Hexagonal AlN layers were grown on Si(111) by gas-source molecular-beam epi taxy with ammonia. The transition between the (7 x 7) and (1 x 1) silicon s urface reconstructions, at 1100 K, was used for in situ calibration of the substrate temperature. The initial deposition of Al, at 1130-1190 K, produc ed an effective nucleation layer for the growth of AlN. The Al layer also r educed islands of SiNx that might be formed due to background NH3 on the si licon surface prior to the onset of epitaxial growth. The transition to two -dimensional growth mode, under optimum conditions, was obtained after the initial AlN thickness of similar to 7 nm. (C) 1999 American Institute of Ph ysics. [S0003-6951(99)04530-1].