AlN Surface Passivation of GaN-Based High Electron Mobility Transistors by Plasma-Enhanced Atomic Layer Deposition

• Main Authors: An-Jye Tzou, Kuo-Hsiung Chu, I-Feng Lin, Erik Østreng, Yung-Sheng Fang, Xiao-Peng Wu, Bo-Wei Wu, Chang-Hong Shen, Jia-Ming Shieh, Wen-Kuan Yeh, Chun-Yen Chang, Hao-Chung Kuo
• Format: Article
• Language: English
• Published: SpringerOpen 2017-04-01
• Series: Nanoscale Research Letters
• Subjects: GaN; High electron mobility transistor (HEMT); Atomic layer deposition (ALD); Current collapse; Surface passivation
• Online Access: http://link.springer.com/article/10.1186/s11671-017-2082-0
• ISSN: 1931-7573; 1556-276X

Abstract We report a low current collapse GaN-based high electron mobility transistor (HEMT) with an excellent thermal stability at 150 °C. The AlN was grown by N2-based plasma enhanced atomic layer deposition (PEALD) and shown a refractive index of 1.94 at 633 nm of wavelength. Prior to deposit AlN on III-nitrides, the H2/NH3 plasma pre-treatment led to remove the native gallium oxide. The X-ray photoelectron spectroscopy (XPS) spectroscopy confirmed that the native oxide can be effectively decomposed by hydrogen plasma. Following the in situ ALD-AlN passivation, the surface traps can be eliminated and corresponding to a 22.1% of current collapse with quiescent drain bias (V DSQ) at 40 V. Furthermore, the high temperature measurement exhibited a shift-free threshold voltage (V th), corresponding to a 40.2% of current collapse at 150 °C. The thermal stable HEMT enabled a breakdown voltage (BV) to 687 V at high temperature, promising a good thermal reliability under high power operation.