Dual-channel 4H-SiC metal semiconductor field effect transistors

4H-SiC metal-semiconductor field effect transistors (MESFETs) with a dual-channel layer are fabricated and characterized. The higher doped lower-channel layer serves to increase the channel current while the lower doped upper-channel layer is used to improve the breakdown voltage. The thickness and doping concentration of the lower-channel layer are 0.08 μm and 5.2 × 1017 cm−3 respectively, while for the upper-channel layer, the values are 0.12 μm and 1.4 × 1017 cm−3 respectively. The dual-channel MESFETs with 1 μm gate length have a saturation drain current density of 280 μA/μm, source–drain breakdown voltage of 145 V and maximum output power density of 4.6 W/mm. These results are improved compared to conventional single channel MESFETs fabricated in this work using the same process with a channel thickness of 0.20 μm and doping concentration of 2.4 × 1017 cm−3.