Fabrication and Low Temperature Characterization of Ge (110) and (100) p-MOSFETs

The Ge p-MOSFETs on (110) substrates using two-step implantation and NiGe contacts have been demonstrated. The record peak mobility of 528 cm²/V·s of the (110) Ge device is measured by the spilt C-V method and can be further enhanced by proper stress. Ge p-FETs on (110) substrates have lower mobility enhancement than (100) devices under compressive strain along the channel. The peak mobility decreases with decreasing temperature due to impurity scattering. The larger density of interface states causes the larger threshold voltage shift from the room temperature to 100 K as compared with Si MOSFETs.