Strain-generated single photon emitters in CVD-grown transition-metal dichalcogenidenanoribbons

Semiconducting transition metal dichalcogenide (TMD) nanoribbons grown via chemical vapor deposition are a novel platform for investigating the effects of microscopic strain on single photon emitters (SPEs) in TMDs. Here, the effects of local strain and the emergence of single photon emitters in single-layer (1L) WSe₂ and 1L-MoS₂ nanoribbons are studied. The nanoribbons are transferred onto arrays of gold nanocones that impose localized strain on sub-100 nm length scales. Due to the nanoribbon geometry, which is more constrained than 2D crystallites, the nanocones generate a more systematically strained system that is more reproducible and void of complex arrays of wrinkles and folds. Correlated AFM topography and cryogenic photoluminescence confirm that SPEs emerge in these systems and are localized to regions where the ribbon is draped over a cone. The strained regions of the nanoribbons host several SPE states that are spectrally isolated from each other by several nanometers and spatially isolated from other SPEs by the distance between adjacent nanocones. The nanoribbon-based SPEs in WSe₂ have linewidths as small as 10 μeV and photon purities of up to 90%, and their excited state lifetimes are longer than similar emitters from nanobubbles. The longer lifetimes signify that the nonradiative decay rates may be smaller in the nanoribbon materials. In contrast, the localized emitters in MoS₂ nanoribbons are considerably dimmer and have linewidths 100 times larger than emitters in WSe₂, more closely resembling states observed in prior studies generated by focused-ion-beam irradiation. These studies reveal how nanoribbons could serve as high-quality nanoscale quantum light sources that benefit from the reduced dimensionality of the quasi-1D structure.