Analysis and Optimal Design of a Novel SiGe/Si Power Diode forFast and Soft Recovery

Abstract

We propose a novel p+ (Si1−xGex)-n−-n+hetero-junction power diode with three-step gradual changing dopingconcentration in the base region, and the structure mechanism isanalysed. The fast and soft reverse recovery characteristics have beenobtained and the optimal design of the changing doping concentrationgradient and the percentage of Ge is carried out. Compared to theconventional structure of p+ (Si1−xGex)-n−-n+with a constant doping concentration, the softness factor S increasesnearly two times, the reverse recovery time and the peak reversecurrent are reduced over 15% for the device with the optimizedconcentration gradient, while the forward drop is almost unchanged.Taking into account of the improvement of the whole characteristics ofthe novel device, we obtain the optimal percentage of Ge to be 20%.