Abstract
Two-dimensional transition metal dichalcogenide semiconductors are intriguing hosts for quantum light sources due to their unique optoelectronic properties. Here, we report that strain gradients, either unintentionally induced or generated by substrate patterning, result in spatially and spectrally isolated quantum emitters in mono- and bilayer WSe2. By correlating localized excitons with localized strain variations, we show that the quantum emitter emission energy can be red-tuned up to a remarkable ∼170 meV. We probe the fine-structure, magneto-optics, and second-order coherence of a strained emitter. These results raise the prospect of strain-engineering quantum emitter properties and deterministically creating arrays of quantum emitters in two-dimensional semiconductors.
Highlights
Two-dimensional transition metal dichalcogenide semiconductors are intriguing hosts for quantum light sources due to their unique optoelectronic properties
We demonstrate that local strain gradients in the 2D crystal offer this capability and we take a first step toward deterministic engineering of the emitter location and optical properties
For further confirmation of the fact that the highly redshifted 0D-X lines and the comb-like emission lines are only observed in the strong strain-gradient regions, we show the evolution of μ-PL spectra as the focus moves from the flat region of the flake to the strong strain-gradient region of the flake
Summary
Sample is shown in Figure 1a; the gray region and four white disks represent the substrate and four etched holes, respectively, and the blue region corresponds to the WSe2 flake. To better understand the origin of the isolated highly redshifted emitters, we estimate the local strain in the 1L WSe2 by analyzing the peak energy of the 2D-X emission at an excitation power of 33 μW. The spectrum at R and elsewhere on the flat 1L region (see Figure 2b) shows only a broad band 0DX ensemble This direct correlation of localized strains and spatial and spectral emitter isolation leads to a robust conclusion that local strain variations disperse the energies of the individual defects in the 0D-X ensemble, resulting in comblike emission within the nominal defect band and much larger red-tuning of a few defects at highly strained positions. Quantitative analysis of strain-induced energetic shifts of excitonic peaks, fine-structure and polarization statistics of strained emitters and Figures S1−S2. (PDF)
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