Point defects and doping in wurtzite LaN

Wurtzite LaN (wz-LaN) is a semiconducting nitride that has piezoelectric and ferroelectric properties, making it promising for applications in electronics, either as a binary compound or in alloys such as LaAlN. The prospects for wz-LaN in devices are influenced by the properties of point defects and impurities; here, we use first-principles density functional theory with a hybrid functional to calculate their formation energies, as well as their atomic and electronic structures. Among native point defects, we find that nitrogen-related defects, both vacancies (${V}_{\mathrm{N}}^{+}$) and interstitials (${\mathrm{N}}_{i}^{\ensuremath{-}}$), are energetically most favorable under most relevant chemical potentials and positions of the Fermi level; ${V}_{\mathrm{N}}^{0}$ may additionally be observed under N-poor conditions, and ${\mathrm{N}}_{i}^{0}$ may be prominent under N-rich conditions. We also investigate the incorporation of oxygen and hydrogen, which will likely be present as unintentional impurities. We find that the ${\mathrm{O}}_{\mathrm{N}}^{+}$ substitutional species readily forms, but oxygen will not lead to $n$-type conductivity due to formation of $DX$ centers and compensation by interstitial defects. Similarly, substitutional ${\mathrm{H}}_{\mathrm{N}}$ and interstitial ${\mathrm{H}}_{i}$ can compensate both $p$- and $n$-type dopants. Our results provide detailed, microscopic guidance for the development of electronic devices based on wz-LaN.