Hybrid density functional study of optically active Er$^{3+}$ centers in GaN

TL;DR

This study uses hybrid density functional calculations to investigate the structure, energetics, and optical activity of Er$^{3+}$ centers and their complexes in GaN, revealing dominant defect configurations and potential energy transfer mechanisms.

Contribution

It provides a detailed first-principles analysis of Er-related defect centers in GaN, identifying the dominant Er$^{3+}$ configuration and its complexes with vacancies and impurities, advancing understanding of luminescence mechanisms.

Findings

Er$_{ m Ga}$ is the dominant Er$^{3+}$ center with low formation energy.

Er$_{ m Ga}$-$V_{ m N}$ has a deep donor level at 0.61 eV.

Multiple optically active Er$^{3+}$ centers are possible in GaN.

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.