Ge<sub>0.95</sub>Sn<sub>0.05</sub> Gate-All-Around p-Channel Metal-Oxide-Semiconductor Field-Effect Transistors with Sub-3 nm Nanowire Width
Yuye Kang, Shengqiang Xu, Kaizhen Han, Eugene Y.-J. Kong, Zhigang Song, Sheng Luo, Annie Kumar, Chengkuan Wang, W. J. Fan, Gengchiau Liang, Xiao Gong
Abstract
We demonstrate Ge 0.95 Sn 0.05 p-channel gate-all-around field-effect transistors (p-GAAFETs) with sub-3 nm nanowire width ( W NW ) on a GeSn-on-insulator (GeSnOI) substrate using a top-down fabrication process. Thanks to the excellent gate control by employing an aggressively scaled nanowire structure, Ge 0.95 Sn 0.05 p-GAAFETs exhibit a small subthreshold swing (SS) of 66 mV/decade, a decent on-current/off-current ( I ON / I OFF ) ratio of ∼1.2 × 10 6, and a high-field effective hole mobility ( μ eff ) of ∼115 cm 2 /(V s). In addition, we also investigate quantum confinement effects in extremely scaled GeSn nanowires, including threshold voltage ( V TH ) shift and I OFF reduction with continuous scaling of W NW under 10 nm. The phenomena observed from experimental results are substantiated by the calculation of GeSn bandgap and TCAD simulation of electrical characteristics of devices with sub-10 nm W NW . This study suggests Ge-based nanowire p-FETs with extremely scaled dimension hold promise to deliver good performance to enable further scaling for future technology nodes.