BICRYSTALLOGRAPHY OF THE EPITAXIAL SYSTEMS "III-V NITRIDES ON SAPPHIRE": THEORY AND EXPERIMENT

A. N. Efimov, A.O. Lebedev, and A. M. Tsaregorodtsev

Ioffe Institute, Polytekhnitcheskaya Str. 26 St.-Petersburg 194021 RUSSIA
smirnov@smirnov.pti.spb.su

Keywords: nitrides, epitaxy, orientation relationship, computer simulation.

Orientation Relationships (OR) for gallium, aluminum or indium nitrides on sapphire substrates have been systematically studied, both theoretically and experimentally, as a function of substrate orientation. By an approach developed in the paper all variety of published ORs has been classified by the natural way into a few types. It is shown, that the dependence of ORs on both sapphire cut orientation and layer compound can not be recognized within the framework of commonly accepted coincidence site lattices concept. Nevertheless, the dependence of ORs on layer compound for (0001) and (1120) sapphire substrate has been successfully described, without using any fitting parameters, by symmetry analysis earlier proposed by the authors and computer Monte Carlo simulation of initial stage of epitaxy. The experimental part of the paper consists in obtaining the nitride layers on sapphire substrate with various orientations and study of ORs, taking into account direction of polar 6 axis, by both conventional X-ray and Cossel line techniques. As results, for the first time the ORs on all close-packed cuts of sapphire (with polarity) have been determined, and new type of OR for aluminum nitride has been found. All experimental data agree with the results of the theoretical consideration.