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ACS Nano. 2016 Sep 27;10(9):8192-8. doi: 10.1021/acsnano.6b03237. Epub 2016 Aug 26.

Optical Gain in MoS2 via Coupling with Nanostructured Substrate: Fabry-Perot Interference and Plasmonic Excitation.

Jeong HY1,2, Kim UJ3, Kim H1,2, Han GH1,2, Lee H4, Kim MS1,2, Jin Y1,2, Ly TH1,2, Lee SY1,2, Roh YG3, Joo WJ3, Hwang SW3, Park Y3, Lee YH1,2.

Author information

1
Center for Integrated Nanostructure Physics, Institute for Basic Science (IBS) , Suwon 440-746, Republic of Korea.
2
Department of Energy Science, Department of Physics, Sungkyunkwan University , Suwon 440-746, Republic of Korea.
3
Device Lab, Samsung Advanced Institute of Technology , Suwon 443-803, Republic of Korea.
4
AE Group, Platform Technology Laboratory, Samsung Advanced Institute of Technology , Suwon 443-803, Republic of Korea.

Abstract

Despite the direct band gap of monolayer transition metal dichalcogenides (TMDs), their optical gain remains limited because of the poor light absorption in atomically thin, layered materials. Most approaches to improve the optical gain of TMDs mainly involve modulation of the active materials or multilayer stacking. Here, we report a method to enhance the optical absorption and emission in MoS2 simply through the design of a nanostructured substrate. The substrate consisted of a dielectric nanofilm spacer (TiO2) and metal film. The overall photoluminescence intensity from monolayer MoS2 on the nanostructured substrate was engineered based on the TiO2 thickness and amplified by Fabry-Perot interference. In addition, the neutral exciton emission was selectively amplified by plasmonic excitations from the local field originating from the surface roughness of the metal film with spacer thicknesses of less than 10 nm. We further demonstrate that the quality factor of the device can also be engineered by selecting a spacer material with a different refractive index.

KEYWORDS:

Fabry−Perot interference; Purcell effect; local field enhancement; molybdenum disulfide; multireflection; photoluminescence

PMID:
27556640
DOI:
10.1021/acsnano.6b03237

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