Exciton Dipole Orientation of Strain-Induced Quantum Emitters in WSe<sub>2</sub>.

Luo, Yue; Liu, Na; Kim, Bumho; Hone, James; Strauf, Stefan · Nano Lett · 2020

basic_science · Level V

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Abstract

Transition metal dichalcogenides are promising semiconductors to enable advances in photonics and electronics and have also been considered as a host for quantum emitters. Particularly, recent advances demonstrate site-controlled quantum emitters in WSe<sub>2</sub> through strain deformation. Albeit essential for device integration, the dipole orientation of these strain-induced quantum emitters remains unknown. Here we employ angular-resolved spectroscopy to experimentally determine the dipole orientation of strain-induced quantum emitters. It is found that with increasing local strain the quantum emitters in WSe<sub>2</sub> undergo a transition from in-plane to out-of-plane dipole orientation if their emission wavelength is longer than 750 nm. In addition, the exciton <i>g</i>-factor remains with average values of <i>g</i> = 8.52 ± 1.2 unchanged in the entire emission wavelength. These findings provide experimental support of the interlayer defect exciton model and highlight the importance of an underlying three-dimensional strain profile of deformed monolayer semiconductors, which is essential to optimize emitter-mode coupling in nanoplasmonics.