First-principles investigation of near surface donor-acceptor pairs in silicon carbide

We recently proposed a quantum science platform¹ utilizing the dipole-dipole coupling between donor-acceptor pairs (DAPs) in bulk materials to realize optically controllable, long-range interactions between defects in solids. Building on this proposal and using first principles calculations, we investigate the physical properties of several DAPs in proximity of different surfaces in 3C-SiC. Our results indicate that the (2x1) hydrogen terminated surface is a promising surface termination, as it doesn’t introduce any surface states in the bandgap and causes minor changes to the DAP properties, compared to those in the bulk; specifically, we only observe a slight increase in both the zero-phonon line energies and the Huang-Rhys factors. Additionally, we explore the possibility of using transitions between surface defects to near-surface donors and acceptors, to orient the dipole moments of the DAPs perpendicular to the surface. Doing so leads to a beneficial increase of the DAPs dipole coupling compared to their bulk counterpart.