Radiation-induced back-channel leakage in SiGeCMOS on silicon-on-sapphire (SOS) technology

We report the first results of a high-energy gamma irradiation experiment o n SiGe CMOS on silicon-on-sapphire (SOS) technology. In contrast to bulk Si CMOS, with increasing total dose the pFET's develop a significant off-stat e leakage, while the nFET's show a reduction in the leakage, which we attri bute to negative charge trapping at the back Si-sapphire interface. Both th e Si and SiGe pFET's showed the enhancement in leakage, suggesting that the leakage mechanism was not related to the SiGe channel. When the devices we re cooled to liquid-nitrogen temperature, the leakage disappears completely , suggesting that the trapping mechanism is strongly temperature dependent.