Impacts of virtual substrate doping on high frequency characteristics of biaxially strained Si PMOSFET

Formation of a parasitic channel in biaxially strained Si channel p-MOSFET, degrades performance of the device. In this paper the effect of SiGe (virtual substrate) doping on formation of parasitic channel and high frequency characteristics of the strained MOSFET has been studied. Simulation results, indicate that increasing virtual substrate's doping from e.g. 4 × 1015 cm−3 to 4 × 1017 cm−3 effectively eliminates parasitic channel by reducing hole concentration from 1 × 1017 cm−3 to 1 × 1011 cm−3 in the parasitic channel. This improves MOSFET's characteristics including parasitic capacitances and channel length modulation. Also it has been demonstrated that the highest unity-gain bandwidth might be achieved at doping level of 4 × 1017 cm−3.