一种新型n-区多层渐变掺杂SiGe/Si功率开关二极管

n^-区掺杂浓度采用多层渐变式结构的p^ (SiC．e)-n^--n^ 异质结功率二极管。对该新结构的反向恢复特性及正反向I-V特性进行了模拟，从器件运行机理上对模拟结果做出了详细的分析。与n^-区固定掺杂的普通p^ (SiGe)-n^--n^ 二极管相比。在正向压降基本不发生变化的前提下，渐变掺杂后的器件反向恢复时间可缩短一半，反向峰值电流能降低33％，反向恢复软度因子可提高1．5倍。并且，随着n^-区渐变掺杂的层数增多，反向恢复特性越好。

A Novel SiGe/Si Power Diode with Multilayer Gradual Changing Doping in the n-Region

A novel SiGe/Si hetero-junction power diode with multilayer gradual changing doping concentration in the n~-region is proposed. Compared with conventional structure of p~+(SiGe)-n~--n~+diode with the constant doping concentration in the n~-region, the reverse recover time of the device with multilayer gradual changing doping can be shorted nearly a half, the peak reverse recovery current can be reduced about 33% and the softness factor S can be increased about 1.5 times, while the forward drop is almost not changed. Furthermore, a further improvement in the reverse recovery characteristics can be achieved by the use of the n~-region consisting of more doping layers.