Field-effect Transport Properties of Monolayer WSe₂ using Nb-doped WSe₂ as Source and Drain

Realizing low-resistance electrical contacts to 2D semiconductors is significant for exploring their exotic quantum phenomena. Here, we present a monolayer WSe₂ field-effect transistor using Nb-doped WSe₂ as source and drain contacts which replace the more commonly used evaporated metal contacts. The Nb-doped WSe₂ bulk crystals with nominal doping concentrations between 0.1% and 5% are grown via chemical vapor transport. The Nb-doped WSe₂ bulk crystals are subsequently exfoliated in flakes with thicknesses between 20 to 30 nm, and the sheet carrier densities are determined by room temperature Hall measurements. The transport properties of our devices show a clear p-type field-effect behavior, which indicates the formation of an effective contact interface between the Nb-doped WSe₂ and the intrinsic WSe₂ layers_.