Modulation Doping of Single-Layer Semiconductors for Improved Contact at Metal Interfaces

Modulation of Contact Resistance of Dual-Gated MoS2 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 MoS₂ 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 MoS₂ 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.