Optical Signatures of Defect Centres in Transition Metal Dichalcogenide Monolayers

TL;DR

This study uses many-body perturbation theory to identify optical signatures of vacancies in transition metal dichalcogenide monolayers, revealing localized excitons and potential quantum emitter applications.

Contribution

It introduces a detailed analysis of metal vacancies' optical signatures, including polarized excitons, and discusses their potential for quantum computing and defect characterization.

Findings

Metal vacancies produce polarized localized excitons.

Defects cause redistribution of excitonic weight between A and B excitons.

Vacancies can serve as qubit candidates for quantum computing.

Abstract

Even 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 exitons 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.