On mechanisms of sublimation growth of AlN bulk crystals

A novel model of bulk AIN crystal grow th by the sublimation technique is d eveloped. The model takes into account both diffusive and convective transp ort of gaseous Al and N-2 and the kinetic limitation of nitrogen adsorption /desorption on AIN surfaces. The maximum growth rate is found to be control led by joint effect of enhancement of the convective species transport in a nearly stoichiometric vapor phase and of the suppression of nitrogen incor poration into the crystal due to low N-2 sticking probability. The interpla y of these effects provides nonmonotonic dependence of the growth rate on p ressure. The theoretical predictions agree well with experimental data repo rted in literature and obtained in this work. (C) 2000 Published by Elsevie r Science B.V. All rights reserved.