EUROPEAN CONGRESS AND EXHIBITION ON ADVANCED MATERIALS AND PROCESSES - EUROMAT 2021

Doping is fundamental to tune the properties of 2D transition metal dichalcogenides for their future integration in the CMOS architecture, hence achieving substitutional doping during growth is of paramount importance. N-type monolayer WSe2 is often exfoliated from bulk crystals and a procedure to directly dope the material is yet to be established. Here, we demonstrate the synthesis of monolayer n-WSe2 via CVD starting from tungstic acid (H2WO4) and zinc selenide (ZnSe). We achieved large WSe2 triangular monolayer flakes, which exhibit n-type of transport which is attribute to donor states due to the incorporation of Zn ions in the lattice. The doping is very stable and the material exhibits good electron mobilities reaching the highest value at 50 cm2V-1s-1. The substitutional doping has been confirmed via secondary ion mass spectroscopy (SIMS), showing Zn inclusions into the individual WSe2 layers and throughout the layers. Our material is of high crystal quality characterized by a sharp room temperature photoluminescence (PL) assessed by the PL spectra evolution from 10 K to room temperature that shows the contribution of neutral and defect-bound excitons, a signal so far reported only in mechanically exfoliated material.