The Theoretical And Experimental Study For 4H-SiC MESFET

Silicon Carbide (SiC) is a very promising candidate for high temperature, high power, high frequency, relatively low noise and radiation hardness applications due to its excellent physical properties such as a wide bandgap, high breakdown voltage, high thermal conductivity, and high saturation electron drift velocity. With excellent figure of merits compared with other types of SiC, 4H-SiC metal-semiconductor-field -effect-transistor (MESFET) is a potential candidate for the applications in HDTV systems, phased array radars and next generation mobile communication base station. However, factors limiting output power and reliability of the devices under high power operation still remain uncertain. The very properties of SiC that make it an attractive semiconductor for electronic device applications also make it hard to process. Reliability of the schottky contact, trap effect and self-heating effect are the important limitation to device performance. The theoretical models and optimized design should be further studied. In this paper, an analysis model for SiC MESFETs DC characteristics has been developed based on the material properties and Multi-parameter mobility model. The small signal equivalent circuit of SiC MESFETs has been studied in detail. The parasitic and intrinsic elements have been extracted with both numerical and analytical methods. Several familiar models for large signal characteristics and nonlinear analysis have been discussed. Then the nonlinear distortion of 4H-SiC MESFETs was analyzed with Volterra model. Based on the above model, the simulations of the schottky contact reliability, trap effect and self-heating effect are presented and their influences on 4H-SiC MESFETs are investigated. 4H-SiC MESFET with an asymmetric gate is fabricated successfully.