NH3/N2 plasma treatment on etched AlGaN surface for high-performance p-GaN HEMTs fabrication

In this work, an NH3/N2 plasma surface treatment technique has been developed to replenish the nitrogen vacancy on the etched AlGaN surface during the p-GaN high-electron-mobility transistors (HEMTs) fabrication. The efficacy of the treatment is confirmed through X-ray photoelectron spectroscopy (XPS) surface characterization. To evaluate the impact of the plasma treatment, three sets of samples with varying etching times are prepared. Remarkably, the drain current of the most severely over-etched device can be recovered from 148 to over 300 mA/mm, accompanied by improved current collapse immunity, a threshold voltage of +1.5 V, and an Ion/Ioff ratio of over 1 x 108. By employing this technique, p-GaN HEMTs can now be fabricated in a uniform and consistent manner.