Tuning Transport and Chemical Sensitivity via Niobium Doping of Synthetic MoS₂

Beyond the intrinsic properties of 2D materials, another advantage is the tunability that follows from their low dimensionality. Here, large-area Nb-doped MoS₂ monolayer films deposited by metal organic chemical vapor deposition that can function as electrical contacts or chemical sensors are demonstrated. Compared to pristine MoS₂, Nb-doped MoS₂ exhibits a relatively faster growth rate and quenched PL due to formation of mid-gap energy bands. When the Nb concentration reaches 5 at%, doped MoS₂ shows clear p-type characteristics, evident by a 1.7 eV shift of the Fermi level toward the valence band maximum. Doping also impacts transport at the metal/MoS₂ interface, demonstrated by Pt–Ir metallization that is Schottky-limited when in contact with undoped MoS₂ but Ohmic on Nb-MoS₂. Moreover, a 50 × improved signal-to-noise ratio is demonstrated in sensing triethylamine compared to undoped MoS₂, with <15 parts-per-billion detection limit.