Evidence for impact ionisation in AlGaN/GaN HEMTs with InGaN back-barrier

Electroluminescence (EL) spectroscopy in combination with drift-diffusion simulations was used to prove the presence of impact ionisation in AlGaN/GaN HEMTs illustrated on InGaN back-barrier devices. Regardless of the level of gate leakage current, which is dominated by contributions such as surface leakage current and others, EL enabled the revealing of hole generation due to impact ionisation. Hole currents as low as 10pA were detectable by the optical technique used.