This SPIE paper by Fan, Leach, Wu, Xiao, Gu, Morkoç, and Handel compares various gate dielectrics in the performance of AlGaN/GaN HFETs. The research evaluates different high-k dielectric materials for metal-insulator-semiconductor HFETs, comparing their effects on threshold voltage, transconductance, gate leakage, breakdown voltage, and low-frequency noise, with the goal of optimizing gate stack design for improved power density, efficiency, and reliability in GaN-based power electronics and RF amplifiers.