Antimony Semimetal Contact with Enhanced Thermal Stability for High Performance 2D Electronics

Abstract

Antimony (Sb) semimetal was studied as a novel contact approach for enabling two-dimensional (2D) material towards advanced electronic device applications. With this approach, an ohmic contact of close to zero Schottky barrier height and contact resistance value of 0.66 kO.µm is obtained between Sb and monolayer (1L) molybdenum disulfide (MoS2). Short-channel Sb-contacted MoS2 field-effect transistors (FET) demonstrated remarkable on-state current above 600 µA/µm and 1000 µA/µm at VDS = 1 V and 2 V, respectively. Comparing to our previous study of tin (Sn) [1] and bismuth (Bi) semimetal contacts [2], Sb contact offers substantially improved thermal stability with a melting point of 630.6 °C as compared to 271.5 °C for Bi and 231.9 °C for Sn semimetals. The comparative electrical characterization of MoS2 FETs with Sb and Bi contacts after progressive thermal treatments demonstrates fully operational Sb-contacted devices after annealing at 400°C in contrast to 300 °C for Bi-contacted devices, indicating the advantage of Sb towards reaching the thermal budget for back-end-of-the-line (BEOL) compatibility, and hence alleviating the major shortcoming of previously studied Bi and Sn semimetals in terms of their thermal stability issue. The study demonstrates the clear benefits of Sb as a novel semimetal contact option with applications in high performance 2D material device towards beyond-silicon electronics technology.