Donor-Acceptor pairs in wide-band-gap semiconductors for quantum technology applications

Donor-acceptor pairs (DAP) in semiconductors, for example boron and nitrogen in diamond, exhibit large electric dipole moments which could enable optically controllable long-range interactions between separated pairs. These interactions would extend over a significantly longer length scale than spin-spin interactions, leading to new ways to connect quantum states in solids. Here, we carry out calculations based on density functional theory (DFT) to investigate the electronic structure and interactions of DAP formed by various substitutional defects in both diamond and SiC. We use the Quantum Espresso code to determine the most stable charge transition states by computing total energy formation diagrams and evaluate zero phonon lines using constrained DFT. In addition, an explicit correction integral for the emission energy of closely separated DAP is considered. Finally, we show that polarization differences between ground and excited states of DAP lead to their unusually large electric dipole moments both in diamond and SiC. Our results indicate that B-N pairs in diamond are challenging to control due to their large electron-phonon coupling while SiC appears to be a suitable candidate material for hosting DAP and to realize long-range optically controllable interactions.