Effects of Processing and Radiation Bias on Leakage Currents in Ge pMOSFETs

The irradiation and annealing responses of Ge pMOSFETs are investigated as a function of device processing. Transmission gate bias is found to be the worst-case irradiation bias condition. Junction leakage increases with total dose, which leads to a decrease in the I
_on
/I
_off
ratio. The I
_on
/I
_off
ratio recovers with room temperature annealing. Both band-to-band tunneling and trap-assisted tunneling contribute to the observed leakage. Device leakage before and after irradiation is found to be sensitive to halo implant dose and the number of Si monolayers at the Ge/insulator interface. Interface trap densities and body leakage also increase with dose and decrease with annealing.