Ab initiodensity-functional supercell calculations of hydrogen defects in cubic SiC

Based on ab initio density-functional calculations in supercells of 3C-SiC, the stable configurations of hydrogen and dihydrogen defects have been established. The calculated formation energies are used to give semiquantitative estimates for the concentration of hydrogen in SiC after chemical vapor deposition, low temperature H-plasma anneal, or heat treatment in high temperature hydrogen gas. Vibration frequencies, spin distributions, and occupation levels were also calculated in order to facilitate spectroscopic identification of these defects. (V+nH) complexes are suggested as the origin of some of the signals assigned earlier to pure vacancies. Qualitative extrapolation of our results to hexagonal polytypes explains observed electrical passivation effects of hydrogen.