Reproducible Ohmic bismuth contacts to $\textrm{MoS}_2$ nanotubes and nanoribbons

Abstract

Attaching metallic contacts to transition metal dichalcogenide nanostructures and in particular to $\textrm{MoS}_2$ has posed significant challenges over the past years. For $\textrm{MoS}_2$ nanotubes and nanoribbons, a highly promising material for field effect transistors as well as quantum electronic devices, this is even more the case due to the small, curved surface. So far all attempts there have led to a wide scatter of contact resistances on the same chip. Recently, for quasi two-dimensional, flat $\textrm{MoS}_2$ flakes, the use of semimetals has led to a breakthrough, making transparent and Ohmic contacts possible. Here, we demonstrate the steps required to reproducibly fabricate contacts to single, vapor phase grown $\textrm{MoS}_2$ nanotubes and nanowires. All devices display finite room-temperature two-point resistances in absence of gating, with a median value of $340\,\textrm{k}Ω$ in a large fabrication series. A detailed analysis elucidates the impact of the different fabrication changes.