Channel Engineering of III-Nitride HEMTs for Enhanced Device Performance

摘要

We report several approaches to improving III-nitride HEMT performances through channel engineering. Based on an Al{sub}0.3Ga{sub}0.7N/Al{sub}0.05Ga{sub}0.95N/GaN, nearly flat transconductance and gain can be obtained at both the low and high drain current levels, a desirable feature for linear power amplifier operation required by advanced wireless system. For devices grown on sapphire substrate, a maximum power density of 3.38 W/mm, a PAE of 45% are obtained at 2GHz. The output third-order intercept point (OIP3) is 33.2 dBm at 2GHz. We also demonstrate an AlGaN/GaN/InGaN/GaN HEMT structure that features a 3-nm thin In{sub}xGa{sub}(1-x)N (x = 0.1) layer inserted into the conventional AlGaN/GaN HEMT structure. Assisted by the InGaN layer's polarization field that is opposite to that in the AlGaN layer, an additional potential barrier is introduced between the 2DEG channel and buffer, leading to enhanced carrier confinement and improved buffer isolation. Using a conventional GaN buffer grown on sapphire substrate, the off-state source-drain leakage current is as low as ～5μA/mm at V{sub}(DS) = 10 V.