High temperature operation of p-GaN/AlGaN/GaN based devices

P-GaN/AlGaN/GaN heterostructure has gained great interest for the feasibility of both n-channel and p-channel devices. Since gallium nitride has large bandgap, high breakdown field, low intrinsic carrier concentration, and high thermal stability, it has huge potential for high temperature electronics as well. In this study, both n-channel and p-channel devices were fabricated on the p-GaN/AlGaN/GaN platform and measured at high temperatures. N-channel device showed stable normally-off operation, since the p-GaN layer depletes the 2D electron gas (2-DEG) in the GaN channel. The p-channel device showed scalability of the threshold voltage depending on the depth of the p-GaN recess. At high temperatures up to 500 °C, n-channel device showed stable threshold voltage, although the on-current decreased slightly due to the degraded 2DEG mobility when temperature exceeds 400 °C. In contrast, D-mode p-channel device showed slight threshold voltage shift towards the negative direction and an increment of the on-current when temperature increases from room temperature to 500 °C. Inverters based on p-channel and n-channel devices are demonstrated, which show stable logic threshold voltage and high gain up to 500 °C. These high temperature devices and circuits will have broad applications in automotive, geothermal, avionics and aerospace.