Modulation of Contact Resistance of Dual-Gated MoS 2 FETs Using Fermi-Level Pinning-Free Antimony Semi-Metal Contacts.

Achieving low contact resistance (R C ) is one of the major challenges in producing 2D FETs for future CMOS technology applications. In this work, the electrical characteristics for semimetal (Sb) and normal metal (Ti) contacted MoS 2 devices are systematically analyzed as a function of top and bottom gate-voltages (V TG and V BG ). The semimetal contacts not only significantly reduce R C but also induce a strong dependence of R C on V TG , in sharp contrast to Ti contacts that only modulate R C by varying V BG . The anomalous behavior is attributed to the strongly modulated pseudo-junction resistance (R jun ) by V TG , resulting from weak Fermi level pinning (FLP) of Sb contacts. In contrast, the resistances under both metallic contacts remain unchanged by V TG as metal screens the electric field from the applied V TG . Technology computer aided design simulations further confirm the contribution of V TG to R jun , which improves overall R C of Sb-contacted MoS 2 devices. Consequently, the Sb contact has a distinctive merit in dual-gated (DG) device structure, as it greatly reduces R C and enables effective gate control by both V BG and V TG . The results offer new insight into the development of DG 2D FETs with enhanced contact properties realized by using semimetals.