2020, Observation of split defect-bound excitons in twisted WSe2/WSe2 homostructure.Applied Physics Letters.

Observation of split defect-bound excitons in twisted WSe₂/WSe₂ homostructure. Applied Physics Letters(117, 153103 (2020))

Abstract:

The excitonic effects in two-dimension transition metal dichalcogenides (TMDCs) and their heterostructures have been extensively investigated. Significantly, the moiré excitons, induced by a moiré superlattice in a twisted heterostructure, have triggered tremendous attention, demonstrating the practicability of artificial excitonic crystals. Besides, recent works have shown that the excitonic states in homostructures also exhibit novel properties worthy of further development. Here, we present a tear-and-stack technique for fabricating a regular or a twisted homostructure. Such a strategy was utilized to reassemble a monolayer WSe₂ into a twisted homostructure, and various excitons from this structure have been identified in the photoluminescence (PL) spectra. Interestingly, the unusual equidistant splitting was firstly observed in the defect-bound excitons. It is believed that this phenomenon is attributed to the various defect states and the local stacking patterns. This interpretation is supported by theoretical calculations, which show the dependence of energy band structure on different defect states and local stacking patterns. These unconventional defect-bound excitons are key building blocks in the research of homostructures that highlight the feasibility of artificially manipulating local excitons for practical applications. 

Keywords: van der Waals homestructures (vdWHs), localized excitons ,transition metal dichalcogenides (TMDCs) 

Link:https://aip.scitation.org/doi/10.1063/5.0015431

Observation of split defect-bound excitons in twisted WSe2WSe2 homostructure.pdf