Abstract
Understanding the luminescence of GaN doped with erbium (Er) requires a detailed knowledge of the interaction between the rare-earth dopant and the nitride host, including intrinsic defects and other impurities that may be present in the host material. We address this problem through a first-principles hybrid density functional study of the structure, energetics, and transition levels of the Er impurity and its complexes with N and Ga vacancies, substitutional C and O impurities, and H interstitials in wurtzite GaN. We find that, in the interior of the material, Er${\rm Ga}$ is the dominant Er$^{3+}$ center with a formation energy of 1.55 eV; Er${\rm Ga}$-$V_{\rm N}$ possesses a deep donor level at 0.61 eV which can assist in the transfer of energy to the 4$f$-electron core. Multiple optically active Er$^{3+}$ centers are possible in Er-doped GaN.
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URL
https://arxiv.org/abs/1509.03908