Ge_0.95Sn_0.05 Gate-All-Around p-Channel Metal-Oxide-Semiconductor Field-Effect Transistors with Sub-3 nm Nanowire...

We demonstrate Ge_0.95Sn_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_0.95Sn_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 × 10⁶, and a high-field effective hole mobility (μ_eff) of ∼115 cm²/(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.