Enhancement-Mode LaLuO3-AlGaN/GaN Metal-Insulator-Semiconductor High-Electron-Mobility Transistors Using Fluorine Plasma Ion Implantation

In this work, enhancement-mode (E-mode) AlGaN/GaN metal-insulator-semiconductor high-electron-mobility transistors (MIS-HEMTs) with high-kappa LaLuO3 (LLO) gate dielectric were fabricated by deploying the CF4 plasma treatment technique in a gate-dielectric-first planar process. CF4 plasma treatment can shift the threshold voltage from -2:3 V [for depletion-mode (D-mode) LLO MIS-HEMTs] to 0.6 V (for E-mode LLO MIS-HEMTs). Transmission electron microscopy (TEM) and X-ray photoelectron spectroscopy (XPS) results suggest that fluorine ions could penetrate through the polycrystalline/amorphous LLO film and be implanted into the (Al) GaN barrier layer. The primary threshold voltage (V-TH) shift mechanism of the E-mode LLO MIS-HEMTs is the negatively-charged fluorine ions in (Al) GaN, while fluorine atoms form chemical bonds with La/Lu atoms in the fluorinated LLO film. The E-mode LLO MIS-HEMTs exhibit a drive drain current density of 352mA/mm at V-GS 2:5 V and a peak transconductance (Gm) of similar to 193mS/mm. Significant suppression of current collapse and low dynamic ON-resistance are obtained in the E-mode LLO MIS-HEMTs under high-drain-bias switching conditions. (C) 2013 The Japan Society of Applied Physics