First-principles prediction of n-type diamond: novel co-doped structure using N and Be impurities

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To address the limitation of diamond-based electronic devices, a comprehensive study on n-type diamond is crucial. A novel dopant structure, nitrogen–beryllium co-doping, is proposed for achieving n-type doping. The dopant structure, electronic property, synthesis route and internal strain are analyzed using first-principles density functional theory. The formation energy and ionization energy of xN–Be (x = 1–4) are compared to elucidate the distinct doping effects associated with varying numbers of N atoms. The formation energy initially decreases and then gradually increases with an incensing number of N atoms. Notably, 3N–Be and 4N–Be exhibit appealing n-type diamond properties, with low ionization energies of 0.30–0.41 eV (3N–Be) and 0.23–0.37 eV (4N–Be). To facilitate the preparation of 3/4N–Be co-doped diamond, a non-molecular synthetic route is proposed, involving the prior generation of the 3N-V and 4N-V. The 3/4N–Be co-doped diamond exhibits relatively small strain energy. Finally, this investigation highlights the potential of 3/4N–Be co-doping as excellent choices for n-type dopants, providing a greater variety of n-type structures with similar ionization energy compared to 4N–Li co-doping.