Effects of Halo Doping and Si Capping Layer Thickness on Total-Dose Effects in Ge p-MOSFETs

The total-dose response of Ge p-MOSFETs and p + -n junction diodes is reported for devices fabricated with several process variations. Radiation-induced reduction of the on-off current ratio increases with halo-doping density. Increasing the number of Si monolayers at the substrate/dielectric interface reduces total-dose sensitivity for p-MOSFETs. Reduced mobility degradation is observed after irradiation for devices with a higher number of Si monolayers. The radiation-induced increase in junction leakage is related to the increasing perimeter component of the leakage current. MOSFETs with a higher number of Si monolayers at the dielectric/substrate interface also have reduced perimeter leakage current. Diode leakage current increases with increasing halo-doping density.