SiC Schottky结反向特性的研究

Study on the reverse characteristics of Ti/6H-SiC Schottky contacts

对Ti 6H SiCSchottky结的反向特性进行了测试和理论分析 ,提出了一种综合的包括SiCSchottky结主要反向漏电流产生机理的反向隧穿电流模型 ,该模型考虑了Schottky势垒不均匀性、Ti SiC界面层电压降和镜像力对SiCSchottky结反向特性的影响 ,模拟结果和测量值的相符说明了以上所考虑因素是引起SiCSchottky结反向漏电流高于常规计算值的主要原因 .分析结果表明在一般工作条件下SiCSchottky结的反向特性主要是由场发射和热电子场发射电流决定的 .

The reverse I(V) measurement and analytic calculation of the electron transport across a Ti/6H-SiC Schottky barrier are presented. Based on the consideration of the barrier fluctuations and the barrier height shift caused by image charge and the applied voltage drop across Ti/SiC interfical layer, a comprehensive analytical model for the reverse tunneling current is developed using a WKB calculation of the tunneling probability through a reverse biased Schottky barrier. This model takes into account the main reverse conduction mechanism, such as field emission, thermionic field emission and thermionic emission. The fact that the simulated results are in good agreement with the experimental data indicates that the barrier height shift and barrier fluctuation can lead to reverse current densities orders of magnitude higher than that obtained from a simple theory. It is shown that the field and thermionic field emission processes, in which carries can tunnel through the barrier but cannot surmount it with insufficient thermal energy, dominate the reverse characteristics of a SiC Schottky contacts in a normal working condition.