Interface and border trapping effects in normally-off Al2O3/AlGaN/GaN MOS-HEMTs with different post-etch surface treatmentsProject supported by the National Natural Science Foundation of China (Grant Nos. 61704124, 11690042, and 61634005)

• Published in: Chinese physics B 2020-10, Vol.29 (10)
• Main Authors: Jing, Si-Qi, Ma, Xiao-Hua, Zhu, Jie-Jie, Zhang, Xin-Chuang, Liu, Si-Yu, Zhu, Qing, Hao, Yue
• Format: Article
• Language: English
• Subjects: AlGaN/GaN MOS-HEMTs; border traps; interface traps; measurement; photo-assisted
• ISSN: 1674-1056
• DOI: 10.1088/1674-1056/ab99bb

Trapping effect in normally-off Al2O3/AlGaN/GaN metal-oxide-semiconductor (MOS) high-electron-mobility transistors (MOS-HEMTs) with post-etch surface treatment was studied in this paper. Diffusion-controlled interface oxidation treatment and wet etch process were adopted to improve the interface quality of MOS-HEMTs. With capacitance-voltage (C-V) measurement, the density of interface and border traps were calculated to be 1.13 × 1012 cm−2 and 6.35 × 1012 cm−2, effectively reduced by 27% and 14% compared to controlled devices, respectively. Furthermore, the state density distribution of border traps with large activation energy was analyzed using photo-assisted C-V measurement. It is found that irradiation of monochromatic light results in negative shift of C-V curves, which indicates the electron emission process from border traps. The experimental results reveals that the major border traps have an activation energy about 3.29 eV and the change of post-etch surface treatment process has little effect on this major activation energy.