A New Method for Relaxation of Elastic Stresses During the Growth of Heteroepitaxial Films

Abstract

In the article, using the example of growing aluminum nitride (AlN) on (110) orientation silicon (Si) with a silicon carbide (SiC) buffer layer, a method for growing a new type of substrates is developed which makes it possible to obtain mechanically unstressed semiconductor heterostructures. A specific feature of the synthesis of this kind of substrates is that the SiC layers used for the growth of AlN films were synthesized by the coordinated atoms substitution method. When this method of growth is used in the Si substrate, some of the Si atoms are replaced by carbon atoms. As a result of the substitution of atoms, the initially smooth Si(110) surface transforms into a SiC surface covered with prism-like growth figures, one side of which is the (111) face and the other is the face. These faces are "substrates" for the further growth of semipolar AlN. The structure and morphology of AlN films have been studied by X-ray diffraction, electron microscopy, and Raman spectroscopy. It was found that the AlN layer is formed by intergrown hexagonal microcrystals, which grow in two directions, and for both orientations of the crystals the following relation is approximately satisfied: AlN || Si(110). It is shown that the half-width of the X-ray rocking curve (FWHM) for the diffraction peak from AlN microcrystals, averaged over the area of the sample, is 20 arc minutes. Raman spectroscopy and X-ray diffraction studies have shown the almost complete absence of mechanical stresses in the AlN layer. A theoretical model is constructed to explain the presence of two orientations of the AlN film on SiC/Si(110) found in the experiment, and a method for controlling their orientation is proposed. It is shown that this morphology of the AlN film makes it possible to use it as a buffer layer for the growth of heterostructures based on gallium nitride and aluminum nitride.