Origin of selective enhancement of sharp defect emission lines in monolayer WSe2 on rough metal substrate

Chaudhary, R and Raghunathan, V and Majumdar, K (2020) Origin of selective enhancement of sharp defect emission lines in monolayer WSe2 on rough metal substrate. In: Journal of Applied Physics, 127 (7).

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Abstract

The defect states in atomically thin layers of transition metal dichalcogenides are promising candidates for single photon emission. However, the brightness of such quantum emission is often weak and is accompanied by undesirable effects such as spectral diffusion and strong background emission. By placing a monolayer WSe 2 directly on a rough gold substrate, here, we show a selective enhancement of sharp defect-bound exciton peaks, coupled with a suppressed spectral diffusion and strong quenching of background luminescence. By combining the experimental data with detailed electromagnetic simulations, we reveal that such selective luminescence enhancement originates from a combination of the Purcell effect and a wavelength dependent increment of the excitation electric field at the tips of tall rough features, coupled with a localized strain-induced exciton funneling effect. Notably, insertion of a thin hexagonal boron nitride sandwich layer between WSe 2 and the Au film results in a strong enhancement of the background luminescence, obscuring the sharp defect peaks. The findings demonstrate a simple strategy of using monolayer WSe 2 supported by a patterned metal film that offers a possibility of achieving quantum light sources with high purity, high brightness, and suppressed spectral diffusion.

Item Type:	Journal Article
Publication:	Journal of Applied Physics
Publisher:	American Institute of Physics Inc.
Additional Information:	The copyright of this article belongs to American Institute of Physics Inc.
Keywords:	Defects; Diffusion; Electric excitation; Electric fields; Electromagnetic simulation; Excitons; III-V semiconductors; Light sources; Luminance; Luminescence; Monolayers; Particle beams; Selenium compounds; Transition metals, Background emissions; Bound exciton peaks; Hexagonal boron nitride; Luminescence enhancements; Single photon emission; Spectral diffusion; Transition metal dichalcogenides; Undesirable effects, Tungsten compounds
Department/Centre:	Division of Electrical Sciences > Electrical Communication Engineering
Date Deposited:	19 Aug 2020 09:36
Last Modified:	19 Aug 2020 09:36
URI:	http://eprints.iisc.ac.in/id/eprint/64874

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