Si diffusion into GaN was studied as a function of encapsulant type (SiO 2 or SiN x) and diffusion temperature. Using a SiO 2 encapsulant, the Si diffusion exhibited an activation energy of 0.57 eV with a prefactor of 2.07 × 10 -4 cm 2 sec -1 in the temperature range 800-1,000°C. An enhancement-mode MgO/GaN-on-Si metal-oxide semiconductor field-effect transistor (MOSFET) was fabricated utilizing Si-diffused regions under the source and drain to provide an accumulated channel. The gate leakage through the undoped GaN was low enough for us to achieve good saturation behavior in the drain-current-voltage characteristics. The devices showed improved transconductance and drain current relative to previous devices with Si-implanted source/drain regions.
- Metal-oxide semiconductor field effect transistor (MOSFET)