4H-SiC MESFET表面陷阱效应研究

Study of the Surface Trap Effect in 4H-SiC MESFET

分析了表面陷阱对4H-SiCMESFET直流和瞬态特性的各种影响。在直流特性上,由表面陷阱引入的附加耗尽层使得饱和电流降低和夹断电压偏移;在瞬态特性上,引起栅延迟以及跨导和输出电导的频散。表面陷阱能级和密度的变化也会影响表面陷阱效应。该文还对栅延迟现象进行了分析,并给出了电子浓度分布随时间的变化。

The surface - trapping effect on DC and transient characteristics in 4H - SiC MESFET are analyzed in this paper. In terms of DC characteristics, due to depletion layer induced by surface -trap, the saturation current will decrease, and the pinch - off voltage will shift. In terms of transient characteristics, the gate -lag phenomenon and the frequency dispersion of transconductance （gin） and output conductance will be found. Also, energy level and density of the surface - trap will influence the surface - trap effect. Meanwhile an analysis on gate - lag is made based on the observation of the electron distribution change relative to time.