title: Engineering light outcoupling in 2D materials.
abstract: When light is incident on 2D transition metal dichalcogenides (TMDCs), it engages in multiple reflections within underlying substrates, producing interferences that lead to enhancement or attenuation of the incoming and outgoing strength of light. Here, we report a simple method to engineer the light outcoupling in semiconducting TMDCs by modulating their dielectric surroundings. We show that by modulating the thicknesses of underlying substrates and capping layers, the interference caused by substrate can significantly enhance the light absorption and emission of WSe2, resulting in a ∼11 times increase in Raman signal and a ∼30 times increase in the photoluminescence (PL) intensity of WSe2. On the basis of the interference model, we also propose a strategy to control the photonic and optoelectronic properties of thin-layer WSe2. This work demonstrates the utilization of outcoupling engineering in 2D materials and offers a new route toward the realization of novel optoelectronic devices, such as 2D LEDs and solar cells.
authors.affiliation: Electrical Engineering and Computer Sciences, University of California , Berkeley, California 94720, United States.
authors.forename: Der-Hsien
authors.initials: DH
authors.lastname: Lien
authors.forename: Jeong Seuk
authors.initials: JS
authors.lastname: Kang
authors.forename: Matin
authors.initials: M
authors.lastname: Amani
authors.forename: Kevin
authors.initials: K
authors.lastname: Chen
authors.forename: Mahmut
authors.initials: M
authors.lastname: Tosun
authors.forename: Hsin-Ping
authors.initials: HP
authors.lastname: Wang
authors.forename: Tania
authors.initials: T
authors.lastname: Roy
authors.forename: Michael S
authors.initials: MS
authors.lastname: Eggleston
authors.forename: Ming C
authors.initials: MC
authors.lastname: Wu
authors.forename: Madan
authors.initials: M
authors.lastname: Dubey
authors.forename: Si-Chen
authors.initials: SC
authors.lastname: Lee
authors.forename: Jr-Hau
authors.initials: JH
authors.lastname: He
authors.forename: Ali
authors.initials: A
authors.lastname: Javey
keywords: 2D materials; Raman; light outcoupling; photoluminescence; substrate interference