TCAD Simulation of Novel Recess Gate Common Drain Dual Channel AlGaN/GaN HEMT for Small Signal Performance

In this paper, DC and RF characteristics of Recess Gate Common Drain Dual Channel (CDDC) AlGaN/GaN HEMT have been investigated. The performance of the device in terms of the various figures of merits including gate-source capacitance, drain current, transconductance, and channel conductance has been studied for different recess depths. The threshold voltage is found to decrease by shifting right with increasing recess depth, even though with deeper recess, transconductance increases. It has also been observed that the device operates in enhancement mode with a minimum gate recess depth of 15 nm or more. With increasing recess depth, the drain current starts decreasing due to an increase in channel resistance. Use of recess technology with Al graded barrier layer enhances the performance in terms of gm, ft, and fmax which are 0.003 S, 23, and 46 GHz, respectively, but utilizing gate recess technology alone in CDDC HEMT further enhances device performance and the maximum gm, ft, and fmax are 0.0442 S, 28.43, and 59.21 GHz. The CDDC HEMT retain its advantage for specific applications including PA, LNA, and RF switch with optimized gate recess and graded barrier layer parameters.