High Power Added Efficiency Enhancement-Mode Γ-Gate RF HEMT With High/Low p-GaN Doping Profile

Abstract

$0.5~\mu $ m enhancement-mode (E-mode) p-GaN $\Gamma $ -gate RF HEMT with engineered Mg doping profile in p-GaN layer was studied for high power amplifier application. With high/low Mg doping profile design in p-GaN, the traditional Ti/p-GaN Schottky gate behavior can be transformed to ohmic-gate after 550°C 3 minutes post-gate annealing. The ohmic-gate design of p-GaN HEMT can minimize poole-frenkel (PF) emission thus the flicker noise and current collapse (C.C) can be improved. A better gate-to-channel modulation ability is also obtained due to precipitous C-VG curve of low Mg ( $1\times 10{^{{19}}}$ cm-3) doping concentration p-GaN layer. The fabricated device achieves a threshold voltage (VTH) of +1.1 V, and shows a low on-resistance (RON) of $1.8~\Omega \cdot $ mm and an off-state breakdown voltage of 206 V. With the engineered Mg doping profile design, a 70% PAE is achieved together with an output power density of 1W/mm at VDS of 10V.