Normally Off AlGaN/GaN MIS-High-Electron Mobility Transistors Fabricated by Using Low Pressure Chemical Vapor Deposition Si3N4 Gate Dielectric and Standard Fluorine Ion Implantation

This letter presents a fabrication technology of enhancement-mode (E-mode) AlGaN/GaN metal-insulator- semiconductor high-electron mobility transistors (MIS-HEMTs) using 10 keV fluorine ion implantation. An 8 nm low-pressure chemical vapor deposition silicon nitride layer was deposited on the AlGaN as gate dielectric and energy-absorbing layer that slows down the high energy (10 keV) fluorine ions to reduce the implantation damage. The E-mode MIS-HEMTs exhibit a threshold voltage as high as +3.3 V with a maximum drain current over 200 mA/mm (250 mA/mm for depletion-mode MIS-HEMTs) and a high on/off current ratio of 10⁹. Meanwhile, the E-mode MIS-HEMT dynamic R_ON is only 1.53 times larger than the static R_ON after off-state V_DS stress of 500 V.