Anisotropic point defects in rhenium diselenide monolayers

Abstract

Summary Point defects in 1T″ anisotropic ReSe 2 offer many possibilities for defect engineering, which could endow this two-dimensional semiconductor with new functionalities, but have so far received limited attention. Here, we systematically investigate a full spectrum of point defects in ReSe 2 , including vacancies (V Se1-4 ), isoelectronic substitutions (O Se1-4 and S Se1-4 ), and antisite defects (Se Re1-2 and Re Se1-4 ), by atomic-scale electron microscopy imaging and density functional theory (DFT) calculations. Statistical counting reveals a diverse density of various point defects, which are further elaborated by the formation energy calculations. Se vacancy dynamics was unraveled by in-situ electron beam irradiation. DFT calculations reveal that vacancies at Se sites notably introduce in-gap states, which are largely quenched upon isoelectronic substitutions (O and S), whereas antisite defects introduce localized magnetic moments. These results provide atomic-scale insight of atomic defects in 1T″-ReSe 2 , paving the way for tuning the electronic structure of anisotropic ReSe 2 via defect engineering.

Hysteresis and Photoconductivity of Few‐Layer ReSe2 Field Effect Transistors Enhanced by Air Pressure

“…In ReSe 2 monolayer, in fact, only a small energy barrier (of ≈84 meV) needs to be overcome to allow external O 2 molecules to dissociate when an O 2 molecule is adsorbed at Se vacancies so that they are subsequently filled by dissociated O atoms. [ 61 ] Therefore, when the laser is switched on at ambient pressure, most traps are already filled, and, as discussed above, the dominant mechanism becomes the photo‐assisted desorption of the electronegative molecules, which returns PPC. At an intermediate pressure, both phenomena impact the photocurrent.…”

Direct characterization of intrinsic defects in monolayer ReSe2 on graphene

“…S6 † conclusively exclude the stable Oand S-substituents at the V Se1 site (which was proposed in ref. 31) due to the mismatch in their STM topographical contrast.…”

Ab initio investigations of a CoBiS monolayer with and without point defects

“…This monolayer is a distorted T-phase, similar to ReX 2 , X = S, Se. 6,25 To determine the magnetic ground-state, three possible spin states, namely, high-spin (HS), intermediate spin (IS), and low-spin (LS) are considered for ferromagnetic and antiferromagnetic ordering. For comparison, the nonmagnetic (NM) state is also considered.…”