Vertical Heterojunction ${Ge}_{0.92}\mathrm{Sn}_{0.08}/\mathrm{Ge}$ GAA Nanowire pMOSFETs: Low SS of 67 mV/dec, Small DIBL of 24 mV/V and Highest $\mathrm{G}_{\mathrm{m},\mathrm{ext}}$ of 870 $\mu \mathrm{S}/\mu \mathrm{m}$

We demonstrate high performance vertical heterojunction Ge0.92Sn0.08/Ge gate-all-around (GAA) nanowire (NW) pMOSFETs enabled by a top-down approach, a self-limiting digital etching and NiGeSn metallization. Thanks to the GAA NW geometry and EOT scaling, low SS of 67 m V /dec, small DIBL of 24 m V/ V, and a high $\mathrm{I}_{\mathrm{ON}}/\mathrm{I}_{\mathrm{OFF}}$ ratio of ~ 10 6 are achieved in the smallest NW device with a diameter down to 25 nm. Furthermore, record high $\mathrm{G}_{\mathrm{m},\mathrm{ext}}$ of ~870 $\mu \mathrm{S}/\mu \mathrm{m}$ and the best quality factor $\mathrm{Q}=\mathrm{G}_{\mathrm{m},\mathrm{ext}}\mathrm{SS}_{\mathrm{sat}}$ of 9.1 are obtained for all reported GeSn-based pFETs.