Improved Linearity by Double-Channel GaN HEMTs with the Ultra-Thin AlN Barrier Layer

In this article, the Gallium Nitride High Electron Mobility Transistors (GaN HEMTs) with the ultra-thin AlN barrier layer is introduced to improve the linearity. Due to the ultra-thin AlN subbarrier layer, the coupling effect between the channels is improved. Compared to the conventional AlGaN/GaN single-channel (CSC) HEMTs, the ultra-thin AlN bottom barrier layer double-channel (UBD) HEMTs exhibit a wider gate voltage swing (GVS) of 4.9 V. In comparison with traditional double-channel HEMTs, the difference between <tex xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">$g_{\mathrm{m}}$</tex> peaks and valleys of UBD HEMTs is smaller. At 3.6 GHz, the higher maximum output current density of 11.3 W/mm is realized by UBD HEMTs, with a maximum power-added efficiency (PAE) of 57 %. These results indicate that the doublechannel structure with an ultra-thin barrier layer holds great potential in the design of high-performance GaN HEMTs.