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Interference‐Enhanced Broadband Absorption of Monolayer MoS 2 on Sub‐100 nm Thick SiO 2 /Si Substrates: Reflection and Transmission Phase Changes at Interfaces
Author(s) -
Kim Eunah,
Cho JinWoo,
Kim Bo Ra,
Nguyen Trang Thi Thu,
Nam YoonHo,
Kim SunKyung,
Yoon Seokhyun,
Kim Yong Soo,
Lee JungHo,
Kim DongWook
Publication year - 2018
Publication title -
advanced materials interfaces
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.671
H-Index - 65
ISSN - 2196-7350
DOI - 10.1002/admi.201701637
Subject(s) - materials science , monolayer , optoelectronics , raman spectroscopy , absorption (acoustics) , wafer , wavelength , reflection (computer programming) , phase (matter) , optics , layer (electronics) , substrate (aquarium) , nanotechnology , chemistry , physics , oceanography , organic chemistry , geology , computer science , composite material , programming language
The optical characteristics of MoS 2 monolayers on SiO 2 /Si substrates with an SiO 2 thickness ranging from 40 to 130 nm are investigated. The measured Raman and optical reflection spectra of the MoS 2 monolayers vary considerably depending on the SiO 2 thickness. The Raman peak intensity of the MoS 2 monolayer on the substrate with an 80 nm thick SiO 2 layer is four times larger than those in the cases of 40‐ and 130 nm thick SiO 2 layers, indicating a significant difference in the absorption at the excitation wavelength. The incident light undergoes anomalous phase changes upon reflection and transmission at the highly absorbing MoS 2 /nonabsorbing SiO 2 or air interfaces. The phase changes at these interfaces in conjunction with those induced by the propagation of light in the SiO 2 layer cause complex interference, which dramatically tunes the absorption spectrum of the MoS 2 layer with changing SiO 2 thickness. Neither wavelength nor the incident angle of light strongly affects the interface phase change. Thus, the MoS 2 monolayers on sub‐100 nm thick SiO 2 /Si substrates exhibit broadband omnidirectional absorption in the visible range. This work demonstrates that SiO 2 /Si wafers, which are the most popular substrates, allow the optical responses of MoS 2 monolayers to be optimized for optoelectronic applications.