Air-stable and efficient electron doping of monolayer MoS2 by salt–crown ether treatment

Abstract

To maximize the potential of transition-metal dichalcogenides (TMDCs) in device applications, the development of a sophisticated technique for stable and highly efficient carrier doping is critical. Here, we report the efficient n-type doping of monolayer MoS₂ using KOH/benzo-18-crown-6, resulting in a doped TMDC that is air-stable. MoS₂ field-effect transistors show an increase in on-current of three orders of magnitude and degenerate the n-type behaviour with high air-stability for ∼1 month as the dopant concentration increases. Transport measurements indicate a high electron density of 3.4 × 10¹³ cm⁻² and metallic-type temperature dependence for highly doped MoS₂. First-principles calculations support electron doping via surface charge transfer from the K/benzo-18-crown-6 complex to monolayer MoS₂. Patterned doping is demonstrated to improve the contact resistance in MoS₂-based devices.