Analysis And Design Of Fast And Soft Recovery SiGe Hetero-junction Power Diodes

With the high frequency trend of power electronic technique development, the switching power diodes must be conducted and turn off very fast, that is, the diodes should have short reverse recovery time, low peak reverse current and soft recovery characteristics. The performance of state-of-the art silicon PiN diodes is now approaching the theoretical limits, and it is apparent that further advances in silicon technology are very difficult because of material properties. Therefore, It is essential to develop novel material switching power diodes.On the base of the study on SiGe material physics characteristic , SiGe/Si hetero-junction characteristic, we dissertate the advantage of SiGe/Si hetero-junction power diodes and establish more accurately physical models and propose two novel kinds of fast and soft recovery p+(SiGe)-n--n+ hetero-junction power diodes: The one is p+(SiGe)-n"-n+ diode with the multiplayer gradual changing doping concentration in the n-region, and the other is p+(SiGe)-n"-n+ diode with ideal ohmic contact on the cathode interface. After simulating the reverse recovery characteristics , the forward and backward I-V characteristics, carries distribution and current vectors et al by MEDICI, the optimal design to some key parameters is proposed. The researching results indicate the reverse recovery characteristics of the device are much improved: the reverse recovery time isremarkably shorted, the peak reverse current is notably reduced and the soft factor S is also increased in various degrees but not notable changed in forward drop when introducing the two kinds of novel structure. Most of the characteristics are far better than the conventional Si and SiGe PiN diode. These improvements are achieved without resorting lifetime killing and thus the devices can be easily integrated into power ICs. This paper is good for design and manufacture of p+(SiGe)-n"-n+ hetero-junction power diodes.