An Improved 4H-SiC MESFET with a Partially Low Doped Channel

An improved 4H-SiC metal semiconductor field effect transistor (MESFET) based on the double-recessed MESFET (DR-MESFET) for high power added efficiency (PAE) is designed and simulated in this paper and its mechanism is explored by co-simulation of ADS and ISE-TCAD software. This structure has a partially low doped channel (PLDC) under the gate, which increases the PAE of the device by decreasing the absolute value of the threshold voltage (V_t), gate-source capacitance (C_gs) and saturation current (I_d). The simulated results show that with the increase of H, the PAE of the device increases and then decreases when the value of N_PLDC is low enough. The doping concentration and thickness of the PLDC are respectively optimized to be N_PLDC = 1 × 10¹⁵ cm^-3 and H = 0.15 μm to obtain the best PAE. The maximum PAE obtained from the PLDC-MESFET is 43.67%, while the PAE of the DR-MESFET is 23.43%; the optimized PAE is increased by 86.38%.