Deep centers in n-GaN grown by reactive molecular beam epitaxy

Abstract

Deep centers in Si-doped $\mathrm{n-}\mathrm{GaN}$ layers grown by reactive molecular beam epitaxy have been studied by deep-level transient spectroscopy as a function of growth conditions. Si-doped GaN samples grown on a Si-doped $n^{+}-\mathrm{GaN}$ contact layer at 800 °C show a dominant trap $C_1$ with activation energy $E_T\text{=0.44\hspace{0.17em}}\mathrm{eV}$ and capture cross-section ${\sigma }_T{\text{=1.3×10}}^{\text{−15}}\hspace{0.17em}{\mathrm{cm}}^{\mathrm{-2}},$ while samples grown at 750 °C on an undoped semi-insulating GaN buffer show prominent traps $D_1$ and $E_1,$ with $E_T\text{=0.20\hspace{0.17em}}\mathrm{eV}$ and ${\sigma }_T{\text{=8.4×10}}^{\text{−17}}\hspace{0.17em}{\mathrm{cm}}^{\mathrm{2}},$ and $E_T\text{=0.21\hspace{0.17em}}\mathrm{eV}$ and ${\sigma }_T{\text{=1.6×10}}^{\text{−14}}\hspace{0.17em}{\mathrm{cm}}^{\mathrm{2}},$ respectively. Trap $E_1$ is believed to be related to a N-vacancy defect, since the Arrhenius signature for $E_1$ is very similar to the previously reported trap $\mathrm{E,}$ which is produced by 1-MeV electron irradiation in GaN materials grown by both metalorganic chemical-vapor deposition and hydride vapor-phase epitaxy.