Improved gate leakage current and breakdown voltage of InAlN/GaN MIS-HEMTs by HfAlOx-based charge-trapping layer dielectric and in situ O3 treatment

In this study, high-performance InAlN/GaN metal-insulator-semiconductor high electron mobility transistors (MIS-HEMTs) are fabricated using HfAlOx-based charge-trapping layer dielectric stack combined with in situ O3 treatment. A positive threshold voltage shift (ΔVTH) of 8.9 V is achieved due to the charge-trapping effect. The device also shows a high Ion/Ioff ratio of ∼1010, a low gate leakage current of ∼10−7 mA/mm, and a relatively high BVDS of 400 V. The suppression of gate leakage current results in an ultra-high gate breakdown voltage of 22.5 V, owing to the superior current blocking capability of the O3-based Al2O3/HfO2 blocking layers and the interface improvement between dielectric and InAlN barrier achieved through in situ O3 treatment. The time-dependent dielectric breakdown measurements reveal the quality and reliability of the dielectric layer, predicting a maximum VGS of 9.66 and 9.31 V for a 10-year lifetime at failure rates of 63.2% and 0.10%, respectively. Additionally, x-ray photoelectron spectroscopy, atomic force microscopy, and multi-frequency C–V measurements further verify the effectiveness of the in situ O3 treatment in the optimization of the dielectric/GaN interface. These results demonstrate a practical approach to significantly improve the performance of InAlN/GaN MIS-HEMTs.