Record Hole Mobility at High Vertical Fields in Planar Strained Germanium on Insulator With Asymmetric Strain

Long channel asymmetrically strained Ge narrow width p-MOSFETs were fabricated from (100) biaxially strained Ge (strain ~ 2.5%) on insulator. Devices with widths of 0.425-15 μm were fabricated with and channel directions. Reducing the mesa width caused mobility to increase for but decrease for channel orientations. The highest mobility was observed for 0.425- μm-wide mesas with channel direction with an enhancement of 45%-50% relative to biaxially strained Ge at N_inv=6×10¹² cm^-2 and a record mobility of 955 cm²/Vs at N_inv=10¹³ cm^-2. Mesas up to 2- μm wide were observed to have enhanced mobilities relative to biaxial Ge, suggesting that even relatively wide mesas can be affected by patterning-induced strain relaxation.