Simultaneous observation of luminescence and dissociation processes of Mg–H complex for Mg-doped GaN

Abstract

Both luminescence properties and dissociation kinetics of Mg–H complex for as-grown Mg-doped GaN are simultaneously investigated by low-energy electron-excited nanoluminescence (LEEN) spectroscopy. Ultraviolet luminescence at 3.2–3.3 eV and blue luminescence at 2.8–2.9 eV are observed as predominant LEEN emissions. In-depth profiles of LEEN emission show that the blue luminescence is the predominant emission for highly Mg-doped GaN. Electron-beam exposure less than $\text{50\hspace{0.17em}}{\mathrm{mC/cm}}^2$ produces an increase of the ultraviolet luminescence intensity and reduction of the blue luminescence intensity. These characteristics suggest that the blue luminescence is due to a transition from hydrogen-related deep donor to Mg acceptor and that the ultraviolet luminescence is due to transitions from conduction band and/or shallow hydrogen donor to Mg acceptor. We propose a kinetic model for dissociation reactions of Mg–H complex during electron exposure, and the reaction rate is evaluated to be ${\text{(3.5±0.3)×10}}^{\text{−3}}\hspace{0.17em}{\mathrm{s}}^{\text{−1}}$ for electron beams with ${\text{3.1×10}}^{\text{−5}}\hspace{0.17em}{\mathrm{A/cm}}^2$ at 5.0 keV.