Abstract
AbstractEven the best quality 2D materials have non‐negligible concentrations of vacancies and impurities. It is critical to understand and quantify how defects change intrinsic properties, and use this knowledge to generate functionality. This challenge can be addressed by employing many‐body perturbation theory to obtain the optical absorption spectra of defected transition metal dichalcogenides. Herein metal vacancies, which are largely unreported, show a larger set of polarized excitons than chalcogenide vacancies, introducing localized excitons in the sub‐optical‐gap region, whose wave functions and spectra make them good candidates as quantum emitters. Despite the strong interaction with substitutional defects, the spin texture and pristine exciton energies are preserved, enabling grafting and patterning in optical detectors, as the full optical‐gap region remains available. A redistribution of excitonic weight between the A and B excitons is visible in both cases and may allow the quantification of the defect concentration. This work establishes excitonic signatures to characterize defects in 2D materials and highlights vacancies as qubit candidates for quantum computing.
Highlights
Even the best quality 2D materials have non-negligible concentrations of and the presence of strongly bound excitons, opening avenues for generation vacancies and impurities
There is an ongoing search for long lived spin states at room temperatures in Transition metal dichalcogenides (TMDs)
While some studies on the optical response of defected TMD supercells exist,[22,23,24] here we present a representative sample of highly converged calculations on defects that have shown potential due to their ease in manufacturing (S vacancy, MoW substitution, (CH2)S substitution) or rich optical features (W vacancy)
Summary
Even the best quality 2D materials have non-negligible concentrations of and the presence of strongly bound excitons, opening avenues for generation vacancies and impurities. The S vacancy is the most commonly found defect in monolayers of WS2 and often assigned to specific features below the optical gap.[18] In the substitution case MoW is quite commonly found in nature, and carbon is a common dopant in semiconductors.[25] Studies have been made on the potential transport applications of TMDs and transition metal carbides.[13,26] In the case of MoS2 experiments point to changes to the electronic structure due to carbon doping, which should translate into new optical features.[15,27]
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