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 MoS(2)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 MoS(2)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 MoS(2)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/MoS(2)interface, demonstrated by Pt-Ir metallization that is Schottky-limited when in contact with undoped MoS(2)but Ohmic on Nb-MoS2. Moreover, a 50 x improved signal-to-noise ratio is demonstrated in sensing triethylamine compared to undoped MoS2, with<15 parts-per-billion detection limit.