Electronic Doping Controlled Migration of Dislocations in Polycrystalline 2D WS₂

Abstract

Migration of dislocations not only determines the durability of large‐scale nanoelectronic and opto‐electronic devices based on polycrystalline 2D transition‐metal dichalcogenides (TMDCs), but also plays an important role in enhancing the performance of novel memristors. However, a fundamental question of the migration dependence on the electronic effects, which are inevitable in practical field‐effect transistors based on 2D TMDCs, and its interplay with different dislocations, remains unexplored. Here, taking WS2 as an example, first‐principle calculations are used to show that the electronic contributions arising from defect states can greatly influence the migration barriers of dislocations. The barrier height can be reduced by as much as 50%, which is mainly attributed to the change in electronic occupation and the band energy of defect levels controlled by electronic chemical potential (Fermi level). The reduced barriers in turn lead to significantly enhanced migration, and thus the plasticity. Since defect levels from dislocations locate deep inside the bandgap, the doping‐induced tuning of barrier height can be achieved at relatively low doping concentration through either chemical doping or electrode gating. The effective electromechanical coupling in 2D TMDCs can provide new opportunities in material engineering for various potential applications.

Structure modulation of two-dimensional transition metal chalcogenides: recent advances in methodology, mechanism and applications

“…Atomic vacancies often induce the reconstruction of the surrounding atoms, which then make the band structures much more complicated such as augmented midgap states. 191 The removal of the MX n units can give rise to enormous transformations of M-X bonds around the atomic vacancies, contributing to the migration of various Fermi levels. 189 In the case of metallic TMDs, atomic vacancies have little impact on their physical behaviour though they induce localized states.…”

Investigation of Structural and Antibacterial Properties of WS2-Doped ZnO Nanoparticles

“…Tungsten is the heaviest transition metal, and its association with sulfur atoms, forming tungsten disulfide (WS 2 ) in the family of common TMDs, became an emerging 2D nanomaterial. − Layered WS 2 is composed of a strong particle covalent bond (S–W) and a weak van der Waals force with an interlayer spacing of 0.7 nm. − WS 2 has a P63/mmc hexagonal crystal layer and at room temperature, the stability of the WS 2 structure is due to the strong S–W–S covalent bonds. − It has a low bandgap that can change from an indirect bandgap (1.3 eV) to a direct and higher bandgap (∼2 eV) when the thickness approaches the monolayer . The band gap energy can be controlled by the number of layers, which confers to WS 2 nanomaterial's great application potential in the field of optics. , The antibacterial activities of WS 2 nanosheets against two representative bacterial strains, Gram-negative Escherichia coli and Gram-positive Staphylococcus aureus, were evaluated by colony-forming unit (CFU) studies .…”