New buffer sublayers for heteroepitaxial III-V nitride films on sapphire substrates

It is suggested to deposit III-V nitride films onto sapphire substrates upo n preliminary deposition of a buffer sublayer of a crystalline material wit h a cubic structure. It is shown experimentally that the deposition of a he teroepitaxial niobium sublayer onto a (0001)-oriented sapphire substrate or a niobium nitride sublayer onto a (11 (2) over bar 0)-oriented Al2O3 subst rate eliminates a 30 degrees rotation of the (0001)-oriented nitride film i n the substrate plane. The elimination of this rotation provides considerab le reduction of the lattice mismatch between the substrate and the nitride film, which, in turn, should increase the degree of crystal perfection of t he film. In addition, the planes of semiconductor nitride films become para llel to the natural cleavage planes of the substrate. This fact provides fo r the possibility of manufacturing a heterolaser with a Fabry-Perot resonat or, in which the role of the mirrors is played by natural cleavage planes o f the film. (C) 2000 MAIK "Nauka/Interperiodica".