Theory and research progress of the barrier inhomogeneities at metal/SiC interface

Silicon carbide (SiC) is a promising candidate for applications in high temperature, high frequency, high power electronics due to its outstanding properties such as wide band gap, high critical electric field and thermal conductivity. SiC Schottky diodes are the earliest commercially available SiC devices. However, since the Schottky barrier height at metal/SiC interface which determines the electrical properties of metal/SiC contact can not be controlled effectively, fabrication of good Ohmic and Schottky contacts is still a challenge to overcome in production of SiC Schottky diodes. Firstly, the barrier theory and carrier transport mechanism of metal/semiconductor were systematically analyzed. According to the non-ideal electrical properties of metal contacts to SiC, the barrier inhomogeneity of SiC Schottky diodes was introduced. Then, the main models including parallel conduction model, Gaussian distribution model, Tung's model and double-barrier Schottky contact model for barrier inhomogeneities were discussed to analyze the non-ideal electrical properties of metal/semiconductor contacts. It was followed by summarizing the research progress of the barrier inhomogeneities of SiC Schottky diodes based on each model. The formation reason and influence factors of the barrier inhomogeneities were explored. Finally, the future research direction in barrier inhomogeneities of metal/SiC was prospected. In order to further improve the performance and stability of SiC Schottky diodes, the mechanism of barrier inhomogeneous, current transport characteristics and their mutual relations are need to be explored.