Band alignment of HfAlO/GaN (0001) determined by X-ray photoelectron spectroscopy : effect of in situ SiH4 passivation

• Main Authors: Liu, Xinke, Liu, Zhihong, Pannirselvam, Somasuntharam, Pan, Jishen, Liu, Wei, Jia, Fang, Lu, Youming, Liu, Chang, Yu, Wenjie, He, Jin, Tan, Leng Seow
• Other Authors: School of Electrical and Electronic Engineering
• Format: Article
• Language: English
• Published: 2015
• Subjects: DRNTU::Engineering::Materials::Metallic materials::Alloys
• Online Access: https://hdl.handle.net/10356/107402; http://hdl.handle.net/10220/25476; http://dx.doi.org/10.1016/j.jallcom.2015.02.139
• Institution: Nanyang Technological University

The energy band alignment between HfAlO and GaN (0001) was characterized using high-resolution x-ray photoelectron spectroscopy (XPS). The HfAlO was deposited using a metal-organic chemical vapor deposition (MOCVD) gate cluster. A valence band offset of 0.38 eV and a conduction band offset of 2.22 eV were obtained across the HfAlO/GaN heterointerface without any passivation. With in situ SiH4 passivation (vacuum anneal+SiH4 treatment) on the GaN surface right before HfAlO deposition, the valence band offset and the conduction band offset across the HfAlO/GaN heterointerface were found to be 0.51 eV and 2.09 eV, respectively. The difference in the band alignment is believed to be dominated by the core level up-shift or chemical shift in the GaN substrate as a result of different interlayers (ILs) formed by the two surface preparations.