The Study Of High Frequency Small Signal Characteristics For 4H-SiC Buried-Channel MOSFET

SiC is a very promising material for high temperature, high power, high frequency, and radiation application because of its superior properties such as wide band gap, high critical breakdown field, high thermal conductivity and high saturation electron drift velocity. But SiC MOSFET suffers from low inversion layer mobility due to high densities of interface states at the SiO2/SiC interface. To improve the performance of SiC MOSFET, a novel 4H-SiC MOSFET, called 4H-SiC buried-channel MOSFET, is studied in this paper.Firstly the operational modes of BC MOSFET are presented. Depending on different bias voltages, the BC MOSFET can be operated in different modes. Then the structure and the physical models are given considering the material parameters of 4H-SiC. Based on the DC analysis, small-signal high frequency characteristics of 4H-SiC BC MOSFET have been simulated using Sinusoidal Steady-State analysis approach by MEDICI. It can be clearly seen that the BC MOSFET is superior in high frequency field by the comparison with conventional MOSFET. Then, the effects of the bias and structure parameters on the cut-off frequency are analyzed. The effects of interface states and temperature are also discussed in this paper.Finally, the process of 4H-SiC BC MOSFET is presented. The results tested show that the SiC BC MOSFETs operate well.