The microstructure and pyroelectric properties of AlxGa1-xN composite epitaxial layers grown on SiC/Si(111) and SiC/Si(110) hybrid substrates by the chloride-hydride epitaxy have been studied. The phenomenon of spontaneous formation of a system of heterojunctions consisting of periodic AlxGa1-xN layers of different composition located perpendicular to the direction of growth, was discovered during the growth of layers. Measurements of the pyroelectric coefficients of these heterostructures have shown that regardless of the orientation of the initial Si substrate and their pyroelectric coefficients have close values of the order of γ~(0.7-1)·10-10 C/cm2K. It is shown that to increase the magnitude of the pyroresponse it is necessary to deposit an AlN layer with a thickness exceeding 1 μm on the AlxGa1-xN/SiC/Si surface. This leads to record values of the pyroelectric coefficient γ~18·10-10 C/cm2K for AlN crystals and films. Keywords: silicon carbide-on-silicon substrates, chloride-hydride epitaxy, AlGaN epitaxial layers, aluminum nitride, gallium nitride, pyroelectric properties.

The growth of InGaN layers on hybrid SiC/Si substrates with orientations (100), (110), and (111) by the HVPE method was studied at temperatures that wittingly exceed the temperature of InN decomposition onto nitrogen atoms and metallic In (1000oC). On substrates with orientations (110) and (111), the formation of InGaN whisker nanocrystals was observed. The shape and growth mechanisms of nanocrystals were investigated. It is shown that nanocrystals nucleate on the (111) surface only inside V-defects formed at the points where screw dislocations exit onto the surface. On the (110) surface, nanocrystals are formed only on pedestals that arise during the film growth. An explanation is given for the difference in the growth mechanisms of nanocrystals on substrates of different orientations. Keywords: InGaN, heterostructures, SiC on Si, silicon, whisker nanocrystals, nanostructures, atomic substitution method

The nucleation mechanism of aluminum nitride films grown by the method ofhydride vapor phase epitaxy on hybrid substrates 3C-SiC/Si(111) istheoretically analyzed. The temperature regions and vapor pressure regionsof components are determined in which the island growth mechanism and thelayer-by-layer growth mechanism are realized. The theoretical conclusionsare compared with the experimental data. The morphology of aluminum nitridefilm on 3C-SiC/Si(111) at the initial growth stage is investigated by themethod of scanning electron microscopy. The methods of controlling thechange of the growth mechanism from the island growth to the layer-by-layergrowth are proposed. Keywords: aluminium nitride, gallium nitride, silicon carbide on silicon, method HVPE, nucleation, wide-bandgap semiconductors, heterostructures.\