Defeitos e co-dopagem em uma monocamada de MoS2

Abstract

In this dissertation we investigate theoretically, through first-principles methods, the eletronic and structural proprieties of defects in monolayers of a molybdenum disulfide (MoS2) in the 2H structure. We consider native defects (atomic vancancies), the sub stitutional acceptor dopant of niobium at a Mo site (MoS2 : N b), the donor dopant resulting from a deposited benzyl viologen (BZV) molecule, (MoS2 + BZV), and, finally, the aceptor-donor pair consisting of these two dopants, (MoS2 : N b + BZV). We show that vacancies modify the MoS2 electronic structure, and that the substitutional Nb acceptor induces a defect state with the absence of an electron, with energy near the top of the valence band. We found three stable configurations of the BZV molecule deposited at the monolayer. All configurations give rise to two occupied states near the bottem of the MoS2 conduction band. We also show that the acceptor-donor pair gives rise to two deep levels near the center of the bandgap, one fully occupied and the other unoccupied.