Investigation of Light-Induced Deep-Level Defect Activation at the AlN/Si Interface

We report on the effect of light-induced deep-level defect activation at the AlN/Si interface of AlGaN/GaN power devices grown on silicon substrates for high-voltage applications. This effect appears as a bump in the $I$--$V$ characteristic at high voltage (HV) when the device is pinched off and exposed to the light. No bump is detected when the device is measured in the dark. We investigate its spectral sensitivity under illumination with different wavelengths. Importantly, this effect can be eliminated by removing the Si substrate. This light-induced bump is related to a charging and discharging mechanism of deep acceptor-like level defects.