Effect of Nickel Doping and Decoration on Electronic Properties of Monolayer Molybdenum Disulfide

Abstract

Doping is an effective method to manipulate the electronic properties of semiconductors. Using density functional theory (DFT), we present an investigation of the properties of nickel (Ni) doped MoS₂ monolayer nanosheets. We studied three possible methods for introducing Ni atoms into the MoS₂nanosheet. First, we examined the effect of Ni atom decoration on the properties of the pristine MoS₂nanosheet.Our calculations revealed that Ni exhibits chemisorption above the Mo atom with an adsorption energy of -3.44 eV, and the band gap has reduced from 1.743 eV in pristine MoS₂ to 1.528 eV. Next, we investigated two possible substitutional doping methods to replace Mo or S vacancies with Ni atoms. Energy considerations showed that the S vacancy substitution is exothermic and most favorable. The Mo vacancy substitution was endothermic and dramatically changed MoS₂'s electronic properties, transforming it from a semiconductor to a conductor. The S vacancy substitution reduced the band gap to 0.682 eV. Nevertheless, all band gaps were direct, as was the case for the pristine MoS₂ monolayer. Density of states (DOS) analysis revealed that the 3d orbital states of the Ni atom exhibit significant hybridization with the d states of the nearest Mo atoms. It is primarily responsible for the change in electronic properties.