Vertical Heterojunction Ge0.92Sn0.08/Ge Gate-All-Around Nanowire pMOSFETs with NiGeSn Contact

Abstract Vertical heterojunction Ge0.92Sn0.08/Ge gate-all-around (GAA) nanowire pMOSFETs fabricated with a top-down approach are reported. With optimized processes, pFETs with nanowire diameters as small as 32 nm were achieved and a decent ION/IOFF ratio of ~3 × 106 was obtained thanks to the GAA nanowire geometry, the GeSn/Ge heterostructure and NiGeSn metallization. A compensating effect between top source resistance and diameter-related electrostatics was identified for pFETs without NiGeSn source. Devices with NiGeSn source showed significant improved ION, ION/IOFF ratio and subthreshold swing (SS) characteristics compared with those without NiGeSn.