Direct growth of doping controlled monolayer WSe₂ by selenium-phosphorus substitution

Although many studies have been carried out on the doping of transition metal dichalcogenides (TMDCs), introducing controllable amounts of dopants into a TMD lattice is still insufficient. Here we demonstrate doping controlled TMDC growth by the replacement of selenium with phosphorus during the synthesis of the monolayer WSe2. The phosphorus doping density was precisely controlled by fine adjustment of the amount of P2O5 dopant powder along the pre-annealing time. Raman spectroscopy, photoluminescence (PL), X-ray photoelectron spectroscopy (XPS), and high-angle annular bright field scanning tunneling electron microscopy (HAADF STEM) provide evidence that P doping occurs within the WSe2 crystal with P occupying the substitutional Se sites. With regard to its electrical characteristics, the hole majority current of P-doped WSe2 is 100-times higher than that of the intrinsic WSe2. The measured doping concentration ranged from ∼8.16 × 1010 to ∼1.20 × 1012 depending on the amount of P2O5 dopant powder by pre-annealing.