Tunable Doping of Rhenium and Vanadium into Transition Metal Dichalcogenides for Two-Dimensional Electronics

TL;DR

This paper introduces a novel chemical vapor deposition method for doping TMDC monolayers with Re and V, enabling tunable electrical properties and significantly improving contact performance in 2D electronic devices.

Contribution

It presents a new controllable growth technique for Re and V-doped TMDCs, demonstrating tunable conductivity and enhanced transistor performance for 2D electronics.

Findings

Electrical conductivity increases up to 10^8 times in V-doped TMDCs.

Tunable semiconductor to metal transition observed in doped TMDCs.

Improved transistor on/off ratios and on-state currents using doped TMDC contacts.

Abstract

Two-dimensional (2D) transition metal dichalcogenides (TMDCs) with unique electrical properties are fascinating materials used for future electronics. However, the strong Fermi level pinning effect at the interface of TMDCs and metal electrodes always leads to high contact resistance, which seriously hinders their application in 2D electronics. One effective way to overcome this is to use metallic TMDCs or transferred metal electrodes as van der Waals (vdW) contacts. Alternatively, using highly conductive doped TMDCs will have a profound impact on the contact engineering of 2D electronics. Here, a novel chemical vapor deposition using mixed molten salts is established for vapor-liquid-solid growth of high-quality rhenium (Re) and vanadium (V)-doped TMDC monolayers with high controllability and reproducibility. A tunable semiconductor to metal transition is observed in the Re and V-doped TMDCs. Electrical conductivity increases up to a factor of 108 in the degenerate V-doped WS2 and WSe2. Using V-doped WSe2 as vdW contact, the on-state current and on/off ratio of WSe2-based field-effect transistors have been substantially improved (from ~10-8 to 10-5 A; ~104 to 108), compared to metal contacts. Future studies on lateral contacts and interconnects using doped TMDCs will pave the way for 2D integrated circuits and flexible electronics.