Performance and Reliability Optimization of Supercritical-Nitridation-Treated AlGaN/GaN High-Electron-Mobility Transistors

According to previous research, supercritical fluid nitridation (SCFN) treatment yields only a limited improvement in AlGaN/GaN high-electron-mobility transistors due to the additional water molecules generated during the SCFN treatment, which reacts with dangling bonds of AlGaN/GaN causing undesirable oxidation, thereby affecting the reliability of the device. In this study, we performed an annealing (ANL) treatment post the SCFN treatment to obtain an ANL-SCFN device with improved electrical performance, owing to the fact that the ANL treatment decreases the gate current leakage and increases the reliability of the device. Furthermore, to verify the decrease in the number of defects in the AlGaN layer of the device after ANL, we conducted a reliability analysis of the negative bias voltage stress (NBS) to observe the deterioration in the output of the device. Previous studies state that the electrons generated through NBS trap the defects in the AlGaN layer, thereby decreasing the electrical properties of the device. However, this study showed that the degradation of the ANL-SCFN device reduced significantly after the NBS analysis, considering the amount of OFF-state leakage decreased due to the ANL treatment, which improved the switching characteristics of the device.