First-principles study of hydrogen retention and diffusion behaviors in 4H-SiC

Here we explicitly present the stability, structure, energetics and diffusion processes of H atom in 4H-SiC with and without intrinsic defects by first-principles calculations. The formation energy and interaction energy of H interstitial at eleven potential interstitial sites are calculated and compared with previous results. Besides, the structure stability of 4H-SiC is evaluated by means of deformation energy. Additionally, the energies of H atom incorporation and solution within the defective 4H-SiC have been calculated and discussed. The minimum energy paths (MEPs) with migration barriers are also calculated for atomic H by interstitial and vacancy-mediated mechanisms. In the defect-free areas of 4H-SiC matrix, interstitial H tends to diffuse three-dimensionally, which is finally trapped into the stable positions of HSi, HC, or TSi on row A. The migration barriers for vacancy-mediated migration display a rather diverse behavior. On the whole, the energy barrier by VC-mediated diffusion is slightly smaller than that by VSi-mediated diffusion, excluding the paths of BC2′→VCA and BC2′→VSiA which show a opposite manner.