Development of SiGe/Si HBT

The development of SiGe/Si HBT in the world is briefly reviewed and our recent research progress in high frequency SiGe/Si HBT is reported. A novel modulation doped quantum well base SiGe/Si HBT is proposed and fabricated. This new structure can reduce the base resistance effectively without increasing the average doping level in base. SiGe/Si HBT with /spl beta/ac over 24000 at 77 K was designed and fabricated. The effects of parasitic barrier induced by boron segregation and outdiffusion in the base were carefully studied, and reasonable width of i-SiGe spacers to prevent these phenomena was obtained by experiment and simulation. The nonideal current of Ib and Ic and their effects on the performance of the device were investigated.