In this paper, the 4H-SiC metal semiconductor field effect transistor with symmetric lightly doped drain (SLDD-MESFET) is improved and a 4H-SiC MESFET with recessed and multi-concentration doped channel (RMDC-MESFET) is proposed. According to the 2-D simulation results, it is found that compared with the SLDD structure, the saturation current of RMDC-MESFET is increased from 373 mA/mm to 480 mA/mm, which is 29% higher. The breakdown voltage remains stable, resulting in a 25% increase in maximum output power density, from 5.89 W/mm to 7.34 W/mm. At the same time, the transconductance of the proposed structure is increased by 28% from 68 mS/mm to 87 mS/mm, resulting in an 18% increase in the cut-off frequency from 21.45 GHz to 25.3 GHz. The DC and RF performances of the RMDC-MESFET are improved simultaneously, so the structure has good prospects for high-power and RF applications.
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