Doping of rhenium disulfide monolayers: a systematic first principles study

Abstract

The absence of a direct-to-indirect band gap transition in ReS₂ when going from the monolayer to bulk makes it special among the other semiconducting transition metal dichalcogenides. The functionalization of this promising layered material emerges as a necessity for the next generation technological applications. Here, the structural, electronic, and magnetic properties of substitutionally doped ReS₂ monolayers at either the S or Re site were systematically studied by using first principles density functional calculations. We found that substitutional doping of ReS₂ depends sensitively on the growth conditions of ReS₂. Among the large number of non-metallic atoms, namely H, B, C, Se, Te, F, Br, Cl, As, P, and N, we identified the most promising candidates for n-type and p-type doping of ReS₂. While Cl is an ideal candidate for n-type doping, P appears to be the most promising candidate for p-type doping of the ReS₂ monolayer. We also investigated the doping of ReS₂ with metal atoms, namely Mo, W, Ti, V, Cr, Co, Fe, Mn, Ni, Cu, Nb, Zn, Ru, Os and Pt. Mo, Nb, Ti, and V atoms are found to be easily incorporated in a single layer of ReS₂ as substitutional impurities at the Re site for all growth conditions considered in this work. Tuning chemical potentials of dopant atoms energetically makes it possible to dope ReS₂ with Fe, Co, Cr, Mn, W, Ru, and Os at the Re site. We observe a robust trend for the magnetic moments when substituting a Re atom with metal atoms such that depending on the electronic configuration of dopant atoms, the net magnetic moment of the doped ReS₂ becomes either 0 or 1 μ_B. Among the metallic dopants, Mo is the best candidate for p-type doping of ReS₂ owing to its favorable energetics and promising electronic properties.