Formation of defects and impurities in MoSx and their effect on electronic properties

Abstract

The authors investigate the thermodynamic and electronic properties of few- and monolayer MoS2 using density functional theory. They calculate the formation energies of S vacancies and the doping effect of C and O under various chemical environments which are commonly observed during MoS2 deposition. The results show that in the oxidizing condition, O readily gets incorporated into the MoS2 layer and assists in C doping. They analyze the bandgap and density of states of MoS2 at different concentrations of defect. They find that the bandgap decreases as the defect concentration increases, wherein the ordering of S vacancies has a more significant influence than that of the other two defects. The S vacancy and C dopants generate deep acceptor gap states within the bandgap of MoS2, while O dopant states are delocalized. They also observe that the carbon dopants form penetrative dimers, which lead to shallow acceptor states. This work contributes to the understanding of defect/impurity incorporation during deposition and prediction of electronic behavior of deposited low-quality MoS2 materials.