Doping 2H-MoTe₂ with a Monolayer Oxide

Direct bandgap van der Waals semiconductors are excellent candidates for optical devices like photodiodes and light emitting diodes due to excellent optical properties and scope for miniaturization. Among these, monolayer Molybdenum Telluride (2H-phase) is a promising material for fabricating optical devices that can work in the Infrared (IR)/ Near-infrared (NIR) regions pertaining to its band gap of 1.1 eV. However, its air sensitive nature makes it extremely hard to find appropriate dopants to form a p-n junction --- heart of any photodetector.<br/>In this work, we demonstrate p-type doping of 2H-MoTe₂ using a monolayer of Tungsten Oxyselenide (TOS) --- an amorphous, stable, and high work-function oxide obtained by self-limiting oxidation of WSe₂. Compared to other p-type doping techniques, this method allows first-passivation-then-doping mechanism that allows to preserve the underlying 2H-MoTe₂. We characterize the doping in MoTe₂ using Raman, PL, and electrical characterization that shows degenerate doping of MoTe₂ using TOS. This is further supported by charge-balance simulations that indicate &gt; 10¹³ cm^-2 doping density. In conclusion, we demonstrate a stable, controllable, degenerate p-type doping technique to dope 2H-MoTe₂ using tungsten oxy selenide (TOS).