Effect of pinch-off current leakage characteristics on microwave power performances of AlxGa1 − xN/GaN HEMTs

The pinch-off current leakage characteristics of AlxGa1 − xN/GaN HEMTs using semi-insulated GaN or Al0.04Ga0.96N buffer layers have been fully investigated. Their gate-drain leakage current densities are only 0.2 and 0.075 mA/mm at VGD of 100 V respectively, which guarantees excellent reverse Schottky breakdown characteristic. Meanwhile, by introducing low-Al AlxGa1 − xN high-resistivity layer, it shows not only a much sharper sub-threshold turn off characteristic with a higher transconductance peak value, but also very lower deep-depletion leakage current. And its better carrier confinement under high VDS greatly improves both the small-signal characteristic and microwave power performance of GaN HEMT devices. In addition, electrical reliability of AlxGa1 − xN/GaN HEMTs at high voltage operation has been greatly improved.

► We investigate the pinch-off current leakage mechanisms of AlxGa1 − xN/GaN HEMTs.
► Low-Al AlGaN high-resistivity buffer layer improves sub-threshold characteristic.
► Deep-depletion current leakage mechanism and carrier confinement have been studied.
► It improves both the small-signal characteristic and microwave power performance.