10 MHz-Switching on GaN Trench CAVET up to 300 °C Operation Enabled by High Channel Mobility

High-frequency, up to 10 MHz, switching of normally-on GaN trench CAVETs was demonstrated using an on-wafer double pulse test (DPT) system, along with high-temperature switching up to 300 °C reported for the first time. By innovatively inserting a low-temperature (LT) GaN interfacial layer to inhibit Mg out-diffusion from p-GaN, a record-high field effect mobility of 1821 cm2/(<inline-formula> <tex-math notation="LaTeX">$\text{V}\cdot \text{s}$ </tex-math></inline-formula>) in a regrown AlGaN/GaN channel was confirmed from device transconductance characteristics, which enabled low-loss high-frequency switching capability of the fabricated device. CAVETs were effectively scaled up to 3-finger structures with reduced specific on-resistance (<inline-formula> <tex-math notation="LaTeX">$\text{R}_{\text {on,sp}})$ </tex-math></inline-formula> to 0.98 <inline-formula> <tex-math notation="LaTeX">$\text{m}\Omega \cdot $ </tex-math></inline-formula> cm2. The device was switched using DPT, showing low turn-off/on times of 2.6/4.8 ns at 1 MHz and 4.5/7.0 ns at 10 MHz switching frequency. The high channel mobility of CAVET not only facilitates robust 10-MHz switching at room temperature but also ensures effective switching functionality even under high-temperature conditions reaching up to 300 °C.