A super junction SiGe low-loss fast switching power diode

Abstract

This paper proposes a novel super junction (SJ) SiGe switching power diode which has a columnar structure of alternating p− and n− doped pillar substituting conventional n− base region and has far thinner strained SiGe p+ layer to overcome the drawbacks of existing Si switching power diode. The SJ SiGe diode can achieve low specific on-resistance, high breakdown voltages and fast switching speed. The results indicate that the forward voltage drop of SJ SiGe diode is much lower than that of conventional Si power diode when the operating current densities do not exceed 1000 A/cm2, which is very good for getting lower operating loss. The forward voltage drop of the Si diode is 0.66 V whereas that of the SJ SiGe diode is only 0.52 V at operating current density of 10 A/cm2. The breakdown voltages are 203 V for the former and 235 V for the latter. Compared with the conventional Si power diode, the reverse recovery time of SJ SiGe diode with 20 per cent Ge content is shortened by above a half and the peak reverse current is reduced by over 15%. The SJ SiGe diode can remarkably improve the characteristics of power diode by combining the merits of both SJ structure and SiGe material.

Novel strained superjunction VDMOS

“…However, a larger Ge mole fraction of Si 1−x Ge x may cause a smaller on-state resistance and more degradation of the blocking voltage. A proper Ge mole fraction of 20% is reported [14,15,16].…”