The Kink Effect at Cryogenic Temperatures in Deep Submicron AlGaN/GaN HEMTs

The kink effect has been studied in deep submicron AlGaN/GaN high-electron mobility transistors by measuring their DC, RF and pulsed performance at cryogenic temperatures. In these devices, the kink effect is mainly due to traps: it appears at T < 260 K and can be removed either by applying, UV light or biasing the gate with short pulses. Its appearance is related to the fluorine-based treatment (CF4/O-2 plasma) used for etching the passivant, treatment which creates traps below and around the gate. This link between the kink and the etching treatment has also been confirmed in optically defined gate devices with different fluorine plasma exposure times.