First-principles investigation of site preference and bonding properties of neutral H in 3C-SiC

SiC can be extensively used in a space environment and other extreme conditions because of its superiority on radiation tolerance. H (proton) that generally exists in the space has large effects on the structure and properties of space materials such as SiC. We have performed the first-principles calculations based on density functional theory to investigate the site preference and bonding properties of neutral H in 3C-SiC. Spin polarization effect for H is taken into account. We show that the supercell should be large enough to diminish the H-H interaction due to the periodic boundary condition. Based on a series of calculations with different exchange-correlation schemes and potentials, we are able to determine the relative stability for different H configurations in SiC. The AB_C (anti-bond of C) configuration is shown to be the most energetically favorable, while the BC (bond center) and T_Si (tetrahedral interstitial of Si) configurations are less stable. We demonstrate that H prefers to form a stronger bond with C rather than Si, particularly in the BC configuration, in contrast to the previous study. Our results will provide a useful reference to the application of 3C-SiC in a space environment.