New 4H-SiC Metal Semiconductor Field Effect Transistors with Double Symmetric Step Buried Oxide Layer for High Energy Efficiency Applications

Abstract

A novel 4H-SiC metal semiconductor field effect transistor (MESFET) device with double symmetric step buried oxide layer is proposed and the mechanism is studied through TCAD simulation. The step buried oxide layer is mainly to reduce the current leakage to the substrate and improve drain current. At the same time, the presence of the oxide layer changes the electric field distribution, reduces the electric field concentration phenomenon, and the breakdown voltage is improved. Due to the presence of the step buried oxide layer, the charge distribution of the device is changed, and the frequency characteristics are improved. When the step buried oxide channel is under the optimized parameter condition, compared with the traditional double-recessed structure 4H-SiC MESFET (DR 4H-SiC MESFET), the direct current (DC) characteristics of the new structure are improved, and the breakdown voltage is increased by 14% to reach 183 V. In radio frequency (RF) characteristics, cut-off frequency is 24.4 GHz, an increase of 11.9 %; maximum operating frequency is 63.9 GHz, an increase of 20.3%; the maximum power added efficiency (PAE) in the L-band and S-band reaches 63.5 %, PAE is 23.7 % higher than the DR structure. At the end of this paper, the new structure is verified for high-energy-efficiency, and the results show that the new structure has great potential in high-frequency applications.