The ab initio study of n-type nitrogen and gallium co-doped diamond

Abstract In order to better understand the influence of different complexes on the diamond co-doping system, N and Ga are chosen as co-dopants in diamond. The properties of several substitutional N_mGa_n (m+n⩽3) complexes with vacancy (Va) in the bulk diamond have been investigated by ab initio density functional technique, including their optimized lattice structures, formation energies, binding energies and thermodynamic transition levels. The calculational results show that N_mGa_n complexes in the donor–acceptor–donor (DAD) configuration can provide ionization energies similar to phosphorus-doped diamond. All other complexes provide deep impurity levels. For the DAD configuration, the adsorption process on the diamond surface has been studied to demonstrate the feasibility of growing diamonds containing N-Ga-N in experiments. The desired complex configuration is not uniquely present in the co-doped system. Investigating these properties of different complexes beyond NGaN provides insight into the N and Ga codoped diamond system, yielding a more comprehensive understanding of its potential and limitations. Our research ideas can also be extended to other co-doped systems and help to evaluate other potential co-dopants for diamond.