Simulation of Trapping Effects in 4H-Silicon Carbide Metal Semiconductor Field Effect Transistor (4H-SiC MESFET)

Abstract

4H-SiC MESFETs have a huge potential in high-power devices atmicrowave frequencies due to their wide bandgap features of high electric breakdown fieldstrength, high electron saturation velocity and high operating temperature.
A Physics-based analytical model for the static I-V characteristics of 4H-SiC MESFETs on high-purity semi-insulating substrates (HPSI) has been proposed. Unlike the existing analytical models, At first semi-insulating nature of the substrate is modeled by considering single trap concentration and compared with theoretical model without taking any trap. Then it is noted that drain current is reduced by some factor due to trap of electron from channel to substrate. Then S.I 4H-SiC substrate is modeled by considering three dominant intrinsic deep acceptor-like traps responsible for carrier compensation in HPSI 4H-SiC substrates for the first time. To further improve the accuracy, field–dependent mobility of electrons in the linear region and channel-length modulation in saturation region are considered in deriving the static I-V characteristics in addition to the substrate effects. The temperature dependence of carrier trapping and detrapping into/from the multiple deep levels and the corresponding I-V variations is analytically studied. Moreover, this model includes source and drain series resistances which are significant in 4H-SiC due to less low-field mobility of electrons compared to GaAs. Some of the simulated results are compared with the reported experimental results to check the validity of the proposed method. This model may serve as a basis to study complicated trapping phenomenon of multiple traps and the related microwave performance of 4H-SiC MESFETs.