Distribution and electronic structure of interstitial hydrogen atoms in β-SiC: a First-Principles study

Abstract

Based on ab initio calculations, the interaction of multiple hydrogen atoms was considered with the “perfect” lattice of β-SiC as the interstitial in the neutral charge state. Starting from the single loading of hydrogen impurities on multi-atom H atoms in β-SiC, the most favorable configurations were established based on the energetic point by formation energies. The Tsc space manifests itself as the preferred option for a single hydrogen atom, and stable H2 can be available at the Tsi site. However, in the presence of H2, the subsequent loading hydrogen interstitials were expelled to the neighboring Tsc box and closed to the carbon pristine atom with C-H and Si-H bond formation at the expense of the Si-C bond cleavage. The calculated binding energy, which exhibits a pronounced increasing trend with the number of hydrogen atoms, opposes H-related cluster formation. Our results corroborate the experimental observation that no H bubbles are generated in a single crystal. Furthermore, the partial and total densities of states were calculated to facilitate the chemical characteristics and modifications of the electronic structures. The low-symmetry fields of hydrogen-related defects result in px, py, and pz orbital states of C and Si splitting, breaking away, and shifting towards the valence band, suggesting that some of the signals assigned to the impurity states appear in the pristine band gap near the new position of the Fermi level.