Assessing the Role of Fluorine in the Performance of AlxGa1−xN/GaN High-Electron-Mobility Transistors from First-Principles Calculations

Doping fluorine into the Al${}_{x}$Ga${}_{1\ensuremath{-}x}$N layer is critical to the performance of enhancement-mode Al${}_{x}$Ga${}_{1\ensuremath{-}x}$N/GaN high-mobility transistors, but the understanding of the role of F in these devices is rather limited. This study starts from the defect properties of F in Al-Ga-N alloy, investigating its interaction with native defects and impurities, as well as its effect on the alloy's Fermi energy. The insight obtained nicely explains the mechanism for the change in a device's electronic performance after doping with F. It also suggests a way to modulate electronic performance, by optimizing the F-incorporation process.