Power switching transistors based on GaN and AlGaN channels

We investigate Al₂O₃/AlGaN interface in GaN MOSHEMTs to engineer channel mobility and threshold voltage suitable for power switching applications. Using oxygen-plasma and annealing treatments, we find the optimal window for high mobility and threshold voltage. Next, we discuss the power switching figure of merit of high composition AlGaN based HEMTs and their potential to achieve large threshold voltages. Finally, we characterize the electrical properties of the interface between Al₂O₃/high composition Al_0.7Ga_0.3N, and measure the conduction band offset of approximately 1 eV with a low positive interface fixed charge density of +2.5 × 10¹² cm^-2.