Growth of metastable cubic AlN by reactive pulsed laser deposition

Aluminum nitride (AlN) thin films were prepared on sapphire (0001) in ambient nitrogen by pulsed laser deposition using a sintered AlN target, and the film structure was evaluated by X-ray diffraction and scanning electron microscopy. 110-oriented hexagonal AlN (alpha-AlN) films were grown at a nitrogen pressure of 10 mTorr. On the other hand, at 40 mTorr the films' central area was partially studded with 111 - and 100-oriented cubic AlN (beta-AlN) crystallites with obvious facets. This area was located on the normal of the irradiation spot on the target, and it corresponded to the region on the film where the highly energetic and dense species were deposited. A nonequilibrium condition and large supply of nitrogen are both important factors for the growth of metastable beta-AlN. (C) 2008 Elsevier B.V. All rights reserved.