Exploring atomic defects in molybdenum disulphide monolayers

Abstract

Defects usually play an important role in tailoring various properties of two-dimensional materials. Defects in two-dimensional monolayer molybdenum disulphide may be responsible for large variation of electric and optical properties. Here we present a comprehensive joint experiment–theory investigation of point defects in monolayer molybdenum disulphide prepared by mechanical exfoliation, physical and chemical vapour deposition. Defect species are systematically identified and their concentrations determined by aberration-corrected scanning transmission electron microscopy, and also studied by ab-initio calculation. Defect density up to 3.5 × 1013 cm−2 is found and the dominant category of defects changes from sulphur vacancy in mechanical exfoliation and chemical vapour deposition samples to molybdenum antisite in physical vapour deposition samples. Influence of defects on electronic structure and charge-carrier mobility are predicted by calculation and observed by electric transport measurement. In light of these results, the growth of ultra-high-quality monolayer molybdenum disulphide appears a primary task for the community pursuing high-performance electronic devices.

Inversion Domain Boundary Induced Stacking and Bandstructure Diversity in Bilayer MoSe2

“…Van der Waals interactions were considered at the vdW-DF level 43,44 with the optB86b 45 exchange functional, which achieves accurate results in calculating structural properties of two dimensional materials 19,20,22,46,47 The authors declare no competing financial interests.…”

Chemical Vapor Deposition of High‐Quality Large‐Sized MoS2 Crystals on Silicon Dioxide Substrates

“…The positions of the Mo peaks indicate the reduction of Mo from Mo 6+ (MoO 3 ) to Mo 4+ (MoS 2 ). The Mo/S ratio obtained from Mo 3 d and S 2 p XPS is about 1:1.97, suggesting that the CVD MoS 2 film is stoichiometric with some S vacancies,36 which were reported as the dominant point defect in CVD‐grown MoS 2 37…”

Repairing atomic vacancies in single-layer MoSe2 field-effect transistor and its defect dynamics

“…21 Fast phototransistors have been demonstrated with the CVD-grown SLM sheets, whose response time is shorter than 25 ms. 22 However, the state-of-art single-layer devices are much more fragile than the bulk devices because even very careful fabrication often causes atomic defects and vacancies in the atomic layers. [23][24][25][26][27][28] The defects also cause more severe influence on the device performance since the quantum paths are greatly suppressed in the 2D electronic transport. 23,24,29 For the SLM FET, such defects lead to various carrier mobilities, 19,24,[30][31][32][33] and defect repairing is the focus of concern during these years.…”