A Remote-Oxygen-Plasma Surface Treatment Technique for III-Nitride Heterojunction Field-Effect Transistors

We present a paper on the influence of an oxygen-plasma treatment technique for III-nitride (III-N) heterojunction field-effect transistors (HFETs) using a plasma-enhanced atomic layer deposition (PE-ALD) system. The oxygen plasma is excited in a remote location to avoid the plasma damage. After the plasma treatment, the threshold voltage was shifted from -0.25 to 0 V and a two-orders-of-magnitude reduction of the drain leakage current was observed in recessed-gate AlGaN/AlN/GaN HFETs. The capacitance-voltage characteristics of gate diodes showed indistinguishable hysteresis. Improved gate-lag and lowered dynamic ON-resistance were also observed in the fabricated AlGaN/AlN/GaN HFETs after the oxygen-plasma treatment. The results indicate that the oxygen-plasma treatment using a PE-ALD system could be a promising approach to improve the device switching performance in III-N HFETs.