Suppression of heavy-ion induced parasitic bipolar effects and SET (Single Event Transient) pulses from SOI-MOSFETs and SOI-CMOS inverters in which SiGe materials were applied for source/drain have been investigated using device simulation. The parasitic bipolar effects could be suppressed by applying SiGe with Ge concentration of 20% or more for source/drain under constant voltage. The duration of SET pulse from SOI-CMOS inverters could be also reduced by applying SiGe. It was confirmed that the duration is determined by the time for expending of accumulated charges in body region of irradiated MOSFET by the driving current of opposite type of MOSFET.l