Oxygen defect dominated photoluminescence emission of ScxAl1−xN grown by molecular beam epitaxy

Abstract

A fundamental understanding and control of impurity incorporation and charge carrier recombination are critical for emerging Sc_xAl_1−xN electronics, optoelectronics, and photonics. We report on the photoluminescence properties of Sc_xAl_1−xN grown by plasma-assisted molecular beam epitaxy with varying growth temperatures and Sc contents. Bright and broad emission comprising a dominant peak at ∼3.52 eV and a weak peak at ∼2.90 eV was observed in Sc_0.05Al_0.95N. The origin of the ∼3.52 eV emission line is attributed to charge carrier recombination from the localized excited state of (V_cation-O_N)^2−/− to its ground state, whereas the second peak at ∼2.90 eV results from charge carrier recombination of isolated ${\mathrm{V}}_{\text{cation}}^{3-/2-}$ to the valence band. We further show that oxygen defect-related emission can be significantly suppressed by increasing growth temperature. This work sheds light on the recombination dynamics of photoexcited carriers in Sc_xAl_1−xN and further offers insight into how to improve the optical and electrical properties of Sc_xAl_1−xN that are relevant for a broad range of applications.