Theory of photo-ionization defects in nano-porous SiC alloys

Abstract

Photoionization experiments have aided in the characterization of defects in numerous materials including nanoporous silicon carbide (SiC) alloys. We report first-principles calculations of dangling bond defect levels in microscopic models of nanoporous SiC. We used hybrid density functional methods to determine the photoionization energies needed to excite electrons from carbon defects into the conduction bands of SiC alloys, including oxidized SiC. We also examine the energetics and electronic structure of carbon dangling bonds with and without oxygen nearest neighbor interactions. Oxidized carbon dangling bond defects have properties that are consistent with recent photoionization experiments in nanoporous oxidized SiC. Hyperfine calculations provide new predictions to be tested experimentally.