Engineered threshold voltage in AlGaN/GaN HEMTs for normally-off operation

This work proposed the normally-off gate-recessed AlGaN/GaN high electron mobility transistors (HEMTs) with more suitable threshold voltages by adjusting the Al mole fraction in the various AlGaN layer thickness under the gate region. It is found that the slope of threshold voltage versus Al mole fraction curves is decreased with decreasing the thickness of AlGaN layer due to the decrease of piezoelectric effect on 2DEG concentration.