Design And Simulation Research On SiC MESFET New Structures

Silicon carbide (SiC), as one of the most promising material in the third semiconductor generation, is widely used in high-temperature, high-radiation, high-power applications due to its unique properties, such as wide band gap, high critical breakdown field, high saturation drift velocity and high thermal conductivity and so on.4H-SiC is considerd as one of the best material for fabricating the metal semiconductor field effect transistors (MESFET). However, it has been found that surface trapping effect also play an important role in device instability. And with a good breakdown performance, MESFET can be widely used in high-voltage field.In order to investage the influence of the surface traps, third different SiC MESFET structures are designed and simulated with the software ISE TCAD. Fisrtly, the DC, transient and AC small-signal characteristics of the buried channel-buried gate structure are simulated and researched, and the technology layout is also designed. Secondly, based on the simulation results of the buried channel-buried gate MESFET, in order to enhance the breakdown voltage, Field-Plated (FP) structure is added and used. The influence of the DC, AC small-signal and breakdown characteristics of the improved structures with the change of the FP length are simulated and discussed. Finally, a "Dual-channel" MESFET is proposed, and the channel parameters are optimized with simulation results of the DC output and breakdown results. The simulation results in this paper show that, the three different structures proposed in this paper can weaken the surface trapping effect, enhance the AC small-signal characteristics, and improve the breakdown performances.