Morphology of facets on vapor-grown AIN crystals

Single crystals of AIN were grown using the sublimation-recondensation meth od. On the Al-terminated surface, (0 0 1) and (1 1 3) facets were observed. On the basal plane facets, step flow growth was revealed by atomic force m icroscopy measured after the growth. The steps were one molecular layer hig h and were arranged in spirals near the outlets of screw dislocations, but consisted of straight segments along the <(1) over bar 1 0 > directions on the most of the surface. We discuss the shape of the steps as the result of competing processes: re-evaporation of deposited species and their diffusi on along the steps. An estimation of the activation energy for diffusion of Al atoms along th steps gave approximately 0.5 eV. (C) 2001 Elsevier Scien ce B.V. All rights reserved.