Growth and structure of GaN layers on silicon carbide synthesized on a Si substrate by the substitution of atoms: A model of the formation of V-defects during the growth of GaN

This paper presents the results of the electron microscopic study of GaN/AlGaN/AlN/SiC/Si(111) structures grown by the metal-organic vapor phase epitaxy. A SiC epitaxial buffer nanolayer has been grown by a new method of substitution of atoms on the Si(111) substrate. It has been found that there is a strong dependence of the density of dislocations and V-defects on the synthesis conditions of SiC and the thickness of the AlN layer. It has been proved experimentally that the creation of a low-temperature AlN insert with a simultaneous decrease in the thickness of the AlN layer to values of no more than 50 nm makes it possible to almost completely prevent the formation of V-defects in the GaN layer. The density of screw and mixed dislocations in the GaN layer of the studied samples lies in the range from 5 $\cdot$ 10$^9$ to 1 $\cdot$ 10$^{10}$ cm$^{-2}$. A theoretical model of the formation of V-defects during the growth of GaN has been developed.