Mobility enhancement in undoped Ge0.92Sn0.08 quantum well p-channel metal-oxide-emiconductor field-effect transistor fabricated on (111)-oriented substrate
We report the dependence of the electrical performance on surface orientations of undoped Ge0.92Sn0.08 quantum well (QW) pMOSFETs on Ge(111) and (001) substrates. (111)-oriented Ge0.92Sn0.08 QW pMOSFETs show a peak μeff of 845 cm2V−1 s−1 and demonstrate a μeff improvement of 25% over (001)-oriented control at an inversion charge density of 5 × 1012 cm−2. We also report that undoped Ge0.92Sn0.08 QW pMOSFETs show a higher μeff than the doped GeSn devices reported in the literature. The high μeff achieved in undoped QW devices is enabled by incorporating high biaxial compressive strain (1.43%) and eliminating dopant impurity scattering in the defect-free channel.