Enhanced Gate Reliability of Ohmic-Like p-GaN Gate HEMT With a Built-in Reverse Diode

A novel ohmic-like p-GaN gate high-electron-mobility transistor (HEMT) with a built-in diode (BD) was proposed and fabricated in this work. Compared with the conventional Schottky-contact type p-GaN gate, ohmic-like contact can avoid the formation of high electric field in the Schottky depletion region and eliminate gate degradation caused by the Schottky junction failure. Good electrical match between the reverse BD and the PIN junction in the gate-stack is critical to device operation, especially at a high gate voltage. The reverse built-in hybrid anode diode (HAD) can withstand a high reverse bias and limit a relatively low gate leakage current (10−1 mA/mm) even under the forward gate voltage of 100 V. No obvious degradation has been observed after the high temperature and longtime high gate voltage stress. Meanwhile, it has negligible impacts on the other characteristics, showing great potential for practical applications.