Distinguishing various influences on the electrical properties of thin-barrier AlGaN/GaN heterojunctions with in-situ SiNx caps

• Published in: Materials science in semiconductor processing 2021-09, Vol.132, Article 105907
• Main Authors: He, Jiaqi, Cheng, Wei-Chih, Jiang, Yang, Fan, Mengya, Zhou, Guangnan, Yang, Gaiying, Jiang, Lingli, Wang, Xiang, Wu, Zhanxia, Wang, Qing, Yu, Hongyu
• Format: Article
• Language: English
• Subjects: In-situ SiNx; Interface charge; Thin-barrier AlGaN/GaN heterojunction; Two-dimensional electron gas
• ISSN: 1369-8001; 1873-4081
• DOI: 10.1016/j.mssp.2021.105907

Understanding the individual contributions of the factors that influence the electrical properties of a material is important for controlling these properties. In this study, the effects of multiple factors on the electrical properties of thin-barrier AlGaN/GaN heterojunctions with in-situ SiNx caps were investigated using step etching and annealing treatments. The sheet density of the two-dimensional electron gas decreased by 5.9% and 29.5% due to the decrease in the piezoelectric polarization of the AlGaN barrier and the variations in interface charges during SiNx removal, respectively, and it recovered greatly by 72% after annealing-induced surface reconstruction. Capacitance-voltage results clearly revealed few interface traps on the heterojunction with the in-situ SiNx cap. Moreover, a maximum output current of 705 mA/mm and threshold voltage hysteresis below 50 mV were achieved by optimizing the in-situ SiNx interlayer on a thin-barrier metal-insulator-semiconductor structure. This study presents an efficient method for modulating the properties of two-dimensional electron gas and provides insights into the functionality of in-situ SiNx passivation on thin-barrier AlGaN/GaN heterojunctions.