Fe-doped buffer layer with graded layered AlGaN/GaN HEMT for millimeter-wave radar applications

The low cost and scalability of silicon substrates have led to increasing attention to AlGaN/GaN high-electron-mobility transistors (HEMTs) on silicon wafer. We developed and simulated the GaN-based HEMT on Si wafer using the Silvaco TCAD software. The performance of rectangular-gate AlGaN/GaN HEMT on Si wafer is examined in detail with respect to the effects of channel length variation, barrier thickness variation, and gate length variation. The performance of this HEMT structure with a gate length of 100 nm and optimized channel layer thickness (CT) of 200 nm has shown a significant I_DS of 1.11 A/mm, a substantial G_m of 329.79 mS/mm, an impressive f_T of 199.40 GHz, and a notable output current of 1.71 A/mm. When the barrier layer thickness (BT) was varied from 6 to 10 nm while maintaining a 200 nm channel layer thickness, the performance declined at higher barrier thicknesses, yielding an I_DS of 0.8 A/mm, a G_m of 206 mS/mm, an f_T of 193.2 GHz, and an output current of 1.26 A/mm. Finally, this HEMT structure demonstrated superior performance with a gate length (LG) of 40 nm, exhibiting a drain current of 1.92 A/mm, a transconductance (G_m) of 465.49 mS/mm, and a cut-off frequency (f_T) of 465 GHz, and output current (I_D) of 2.11 A/mm. The optimized device structure’s high-power performance without compromising RF performance, they are suitable for millimeter-wave radar applications.