Exploring the Performance of GaN Trench CAVETs from Cryogenic to Elevated Temperatures

Xinyi Wen¹Kwang Jae Lee¹Hayao Kasai^1,2Maliha Noshin¹Chuanzhe Meng¹Srabanti Chowdhury^1*

• ¹Department of Electrical Engineering, School of Engineering, Stanford University, Stanford, California, United States
• ²Research Institute for Advanced Material and Devices, Corporate R&D Group, Kyocera, Japan

The fabricated GaN trench current aperture vertical electron transistors (CAVETs) were characterized across a wide temperature range for the first time, including in-situ cryogenic measurements down to 10 K and ex-situ thermal shock testing at elevated temperatures of 773 K and 1073 K. The device featured a highly conductive AlGaN/GaN channel regrown on p-GaN following trench etching. As temperature decreased, the field-effect mobility in the regrown two-dimensional electron gas (2DEG) channel increased from 1886 cm 2 /(V•s) at 296 K to 3577 cm 2 /(V•s) at 10 K. The device maintained a stable threshold voltage (VTH). The subthreshold slope (SS) decreased from 98.32 mV/dec to 51.31 mV/dec, and the Ion/Ioff ratio increased from 3×10 9 to 9×10 10 over the same temperature range. The specific on-state resistance (Ron,sp) decreased from 1.02 mΩ•cm 2 at 296 K to 0.586 mΩ•cm 2 at 10 K. Furthermore, 1-minute thermal shock testing was conducted as a preliminary method to assess the resilience of trench CAVET at elevated temperatures. The device kept FET functionality after exposure to 773 K, albeit with reduced current. Testing at 1073 K resulted in more significant performance degradation, including a sharp increase in Ron,sp and failure in achieving pinch-off due to a pronounced surge in gate leakage.