Performance Improvement by Enhancing Passivation Layer of p-Type GaN High-Electron Mobility Transistors With Supercritical Oxygen Treatment

In this work, the supercritical oxygen treatment is proposed to passivate the defects of enhancement-mode p-GaN high-electron mobility transistors. After the treatment, the treated device gets enhanced in ON-state current and transconductance without changing the threshold voltage. Thus, the supercritical oxygen may not affect Mg doping concentration of the p-GaN layer, degrading the p-GaN layer after the treatment. The statistical analysis indicates uniformity of devices is improved after the treatment. The gate lag and pulsed $\text{I}_{\text {D}}$ - $\text{V}_{\text {D}}$ measurements are proposed to examine the interface between the passivation layer and the AlGaN layer. The few trapped electrons in defects exhibit the suppression of the charge trapping effect. Based on these results mentioned above, the physical model is proposed to explain the phenomenon. The pristine passivation layer has a number of dangling bonds which capture the electrons and lead to the charge trapping effect. The supercritical oxygen permeates into material matrix, repairing the dangling bonds. Therefore, the technique exhibits potential for power device improvement, enabling effective practical application in the future.