Analysis of High-Frequency Behavior of AlGaN/GaN HEMTs and MIS-HEMTs under UV Illumination

• Published in: ECS journal of solid state science and technology Vol. 10; no. 5; pp. 55004 - 55009
• Main Authors: Chen, Kun-Ming, Lin, Chuang-Ju, Nagarajan, Venkatesan, Chang, Edward Yi, Lin, Chao-Wen, Huang, Guo-Wei
• Format: Journal Article
• Language: English
• Published: IOP Publishing 01.05.2021
• ISSN: 2162-8769; 2162-8777
• DOI: 10.1149/2162-8777/abf9eb

The high-frequency characteristics of AlGaN/GaN high-electron-mobility transistors (HEMTs) and metal-insulator-semiconductor HEMTs (MIS-HEMTs) are investigated under ultraviolet (UV) radiation with 365 nm wavelength. When HEMTs and MIS-HEMTs are illuminated with an UV source, their drain currents increase apparently owing to the generated photocurrent. Nevertheless, they show different high-frequency response to the UV light. For HEMTs, the peak cutoff frequency (f T ) and maximum oscillation frequency (f max ) of illuminated devices are 20% and 10% higher than those in dark condition, respectively, owing to the increased transconductance. For MIS-HEMTs, however, their high-frequency performances are degraded when transistors are subject to light exposure. The degradations of peak f T and f max are around 3.7% and 18%, respectively. The small-signal model parameters relevant to the high-frequency characteristics were extracted to explain these phenomena. Additional trapped charges in the SiN gate dielectric induced by UV light would be responsible for the degraded high-frequency parameters in illuminated MIS-HEMTs. These experimental results are important for designing a suitable GaN-based HEMT for optoelectronic applications.