Native Defects, Diffusion, Self-Compensation, and Boron Doping in Cubic Silicon Carbide

Abstract

ABSTRACTWe report the results of a comprehensive theoretical investigation of the effects of stoichiometry and boron doping on the properties of cubic SiC. Supercell calculations using ab initio pseudopotentials show that the lowest energy defect in Si-rich n-type and intrinsic SiC is the electrically inactive Sic antisite, while VC++ is the lowest energy defect in p-type SiC. The electrons released by the carbon vacancies compensate acceptor dopants and lead to strong self-compensation effects when doping occurs during the growth of crystal. In C-rich SiC the dominant defect for all Fermi level positions is the electrically inactive CSi antisite. In stoichiometric and Si-rich cubic SiC, the BC site is energetically preferred, while BC and BSi have similar incorporation energies in C-rich material. In heavily doped p-type SiC the diffusion of BC proceeds by the dissociative (Frank-Turnbull) mechanism.