SiC肖特基二极管势垒不均匀分布理论与研究进展

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

碳化硅(SiC)半导体具有宽禁带、高临界击穿电场、高热导率等优异的性能,在高温、高频和大功率器件领域具有广阔的应用前景.SiC肖特基二极管是最早商用化的SiC器件,然而,由于决定金属接触性能的肖特基势垒无法得到有效控制,高性能的SiC欧姆接触和肖特基接触制备仍然是SiC肖特基二极管研制中的关键技术难题.基于此,首先对金属/半导体肖特基接触势垒理论和载流子运输机制做了系统分析,根据金属/SiC接触实验中呈现的非理想电学特性,引出SiC肖特基二极管势垒不均匀分布问题;然后对分析势垒不均匀分布的平行传导模型、高斯分布模型、Tung模型、双势垒模型等进行讨论,用各模型分析金属半导体接触呈现的非理想电学特性.接着针对各模型分别综述了SiC肖特基二极管势垒不均匀分布研究的重要进展,探究势垒不均匀分布的形成原因及影响因素;最后,对金属/SiC接触势垒不均匀分布未来的研究方向进行了展望,要进一步提高SiC肖特基二极管的性能及稳定性,金属/SiC接触界面势垒不均匀分布形成机理、电流输运特性及其相互关系还有待进一步深入.

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.