High-Performance WSe$_{\mathrm{2}}$, MoS$_{\mathrm{2}}$, and MoSe$_{\mathrm{2}}$ Transistors Enabled by a New Contact Strategy

Fabrication of high-performance transistors of transition metal dichalcogenides (TMDs) including WSe$_{\mathrm{2}}$, MoS$_{\mathrm{2}}$, and MoSe$_{\mathrm{2\thinspace }}$has been a major challenge in 2D electronics. The performance of current metal-contacted TMDs is limited by the presence of a significant Schottky barrier in most cases. Here we introduce a new strategy for fabricating low-resistance ohmic contacts to a variety of TMDs. We demonstrate low contact resistance $\approx $ 0.3 k$\Omega \mu $m, high on/off ratios up to \textgreater 10$^{\mathrm{9}}$, and high drive currents exceeding 320 $\mu $A $\mu $m$^{\mathrm{-1\thinspace }}$in few-layer WSe$_{\mathrm{2}}$ field-effect transistors (FETs). These favorable characteristics are combined with a two-terminal field-effect hole mobility $\mu_{\mathrm{FE}} \quad \approx $ 2x10$^{\mathrm{2}}$ cm$^{\mathrm{2\thinspace }}$V$^{\mathrm{-1}}$s$^{\mathrm{-1}}$ at room temperature, which increases to \textgreater 2x 10$^{\mathrm{3}}$ cm$^{\mathrm{2\thinspace }}$V$^{\mathrm{-1\thinspace }}$s$^{\mathrm{-1}}$ at cryogenic temperatures. We observe a similar performance also in MoS$_{\mathrm{2}}$ and MoSe$_{\mathrm{2}}$ FETs. *We acknowledge the partial support by NSF grant number DMR-1308436 and the WSU Presidential Research Enhancement Award.