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在考虑到各种物理机制如载流子-载流子散射、俄歇复合、禁带窄化效应及结温效应等的基础上,数值模拟分析了SiGe/Si功率开关二极管的各种温度依赖特性。对Si和SiGe/Si功率二极管而言,温度对器件的正向压降VF、反向击穿电压VB以及反向漏电流JR的影响规律基本相似,即随着温度的升高,正向压降降低,击穿电压增加,反向漏电流迅速提高。然而在相同的温度下,与Si功率开关二极管相比,SiGe/Si二极管(20%Ge含量)的正向压降降低了近0.1V(在正向电流密度10A/cm2的情况下),反向恢复时间缩短了一半以上,反向峰值电流密度也下降了约三分之一,软度因子S提高了2倍多。SiGe二极管的另外一个重要优点是其反向恢复特性受温度影响很小。当温度从300K增加到400K时,Si功率二极管的反向恢复时间增加了近1倍,而SiGe/Si二极管(20%Ge含量)的反向恢复时间基本保持不变。SiGe/Si功率开关二极管的一个缺点是在高温下产生较大的漏电流,但这可以通过适当降低Ge含量来改善。Ge的引入为器件设计提供了更大的自由度,其含量对器件特性有重要影响。为了获得低的正向压降和短的反向恢复时间,应该提高Ge的含量,但Ge含量增加将导致大的漏电流,因此Ge含量的大小应该优化折衷考虑。
Based on various physical mechanisms such as carrier-carrier scattering, Auger recombination, band-gap narrowing effect and junction temperature effect, various temperature dependences of SiGe / Si power switching diodes are numerically simulated characteristic. For Si and SiGe / Si power diodes, the influence of temperature on the device forward voltage drop VF, reverse breakdown voltage VB and reverse leakage current JR are basically similar, that is, as the temperature increases, the forward voltage Drop down, the breakdown voltage increases, the reverse leakage current increases rapidly. However, at the same temperature, the forward voltage drop of the SiGe / Si diode (20% Ge content) is reduced by nearly 0.1 V (in the case of a forward current density of 10 A / cm2) compared to the Si power switch diode, The recovery time was reduced by more than half, reverse peak current density decreased by about one-third, and the softness factor S increased more than twice. Another important advantage of SiGe diodes is that their reverse recovery characteristics are less affected by temperature. When the temperature is increased from 300K to 400K, the reverse recovery time of Si power diode nearly doubled while the reverse recovery time of SiGe / Si diode (20% Ge content) remained almost unchanged. A disadvantage of SiGe / Si power switching diodes is that they produce large leakage currents at high temperatures, but this can be improved by appropriately reducing the Ge content. The introduction of Ge provides more freedom for device design, and its content has a significant impact on device characteristics. In order to obtain low forward voltage drop and short reverse recovery time, the content of Ge should be increased. However, the increase of Ge content will lead to large leakage current. Therefore, the content of Ge should be optimized and compromised.