Insight into interface electrical properties of metal–oxide–semiconductor structures fabricated on Mg-implanted GaN activated by ultra-high-pressure annealing

• Published in: Applied physics letters 2022-02, Vol.120 (8)
• Main Authors: Wada, Yuhei, Mizobata, Hidetoshi, Nozaki, Mikito, Kobayashi, Takuma, Hosoi, Takuji, Kachi, Tetsu, Shimura, Takayoshi, Watanabe, Heiji
• Format: Article
• Language: English
• Subjects: Accumulation; Annealing; Applied physics; Capacitance-voltage characteristics; Capacitors; Electrical properties; Field effect transistors; Gallium nitrides; High pressure; High temperature; Hole mobility; Ion implantation; Magnesium; Metal oxide semiconductors; MOS devices; MOSFETs; Semiconductor devices; Silicon dioxide
• ISSN: 0003-6951; 1077-3118
• DOI: 10.1063/5.0081198

GaN-based metal–oxide–semiconductor (MOS) devices, such as n- and p-type capacitors and inversion- and accumulation-type p-channel field effect transistors (MOSFETs), were fabricated by Mg-ion implantation and ultra-high-pressure annealing (UHPA) under 1-GPa nitrogen pressure. Even though UHPA was conducted at 1400 °C without protective layers on GaN surfaces, n-type MOS capacitors with SiO2 gate dielectrics formed on non-ion-implanted regions exhibited well-behaved capacitance–voltage characteristics with negligible hysteresis and frequency dispersion, indicating distinct impact of UHPA in suppressing surface degradation during high-temperature annealing. Efficient activation of the implanted Mg dopants and reasonable hole accumulation at the SiO2/GaN interfaces were also achieved for p-type capacitors by UHPA, but the fabricated inversion- and accumulation-type p-channel GaN MOSFETs were hardly turned on. The findings reveal extremely low hole mobility at GaN MOS interfaces and suggest an intrinsic obstacle for the development of GaN-based MOS devices.