Off-State Negative Differential Capacitance AlGaN/GaN Heterostructures in cryogenic temperature

Abstract

There are few reports on the degradation phenomenon and mechanism of AlGaN/GaN heterojunction field-effect transistors (HFETs) operating at cryogenic temperature. In this paper, the off-state capacitance of AlGaN / GaN HFETs at cryogenic temperature and the room temperature was investigated. The negative differential capacitance at 77 Κ and 300 Κ is 11.26 F and 0.69 F, respectively. The capacitance was tested at different temperatures, which showed that the negative differential capacitance came from low-temperature conditions. At room temperature, the resistance was increased sharply under the gate of the device off-state. At this time, the current leakage channel was turned on, the phenomenon of negative differential capacitance was caused by an accumulation of electrons. Through the C-V test at different frequencies at 77 K, it reflects the relationship between the trap level, the off-state leakage current, and the negative differential capacitance. This article provides suggestions for the application of GaN-based radio frequency devices in cryogenic temperature environments.