Atomically Thin MoS 2 Narrowband and Broadband Light Superabsorbers

Cho

et al. 2018

Adv Materials Inter

bandgap energy of TMDCs is in the visible range, and thus intensive research efforts have been devoted to realize highefficiency TMDC-based optoelectronic devices. [1][2][3][4][5][6][7] TMDC materials have usually been prepared on SiO 2 /Si wafers by mechanical exfoliation from the bulk or thin film deposition for physical characterization and device fabrication. After TMDC sample preparation, Raman and photoluminescence (PL) spectroscopic measurements are usually performed to identify the thickness and bandgap of the sample. [8][9][10][11][12][13][14][15][16][17][18][19][20][21] The optical absorption and emission signals of the sample become larger as the electric field (E-field) intensity of the incident light in the sample increases. In the SiO 2 /Si substrates, the light undergoes multiple reflections in the SiO 2 layer, leading to interference between its partial waves. Local maxima of the E-field intensity appear when the SiO 2 thickness is equal to (2m − 1)λ/4n SiO2 , where m is a positive integer, λ is the light wavelength, and n SiO2 is the refractive index of SiO 2 , which are identified as Fabry-Perot (FP) resonances. [9][10][11][12][13] At every FP resonance, TMDC layers on SiO 2 /Si substrates can produce very strong Raman and PL intensities. To take advantages of the FP resonance, the dielectric layer is at least a quarter-wave in thickness and most of the researchers have used SiO 2 /Si substrates with ≈300 nm thick SiO 2 layers. [9][10][11][12][13] The light-matter interactions in extremely thin TMDC layers can be strengthened using plasmonic nanoantennae, photonic nanostructures, and the FP cavities. [11,[13][14][15][16][17][18][19][20] Generally, the absorption enhancement is observed only within narrow ranges of the wavelength and angle of the incident light. [9][10][11][12][13][14][15][16][17][18][19][20] To aid material characterization, we can choose an optimal nanostructure to maximize the absorption of a TMDC sample at a specific wavelength. However, such wavelength-and anglesensitive absorption is inappropriate for some applications, including photovoltaics, photodetection, and photocatalysis. [5][6][7] As an alternative approach, Jariwala et al. [7] demonstrated nearunity, broadband absorption in <15 nm thick TMDC layers on Ag and Au back-reflecting substrates. Because TMDC materials usually have a complex refractive index n n ik  = + with an extremely high extinction coefficient (k) in the visible spectrum, 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 r...

mentioning

confidence: 99%

mentioning

confidence: 99%

mentioning

confidence: 99%

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Interference‐Enhanced Broadband Absorption of Monolayer MoS₂ on Sub‐100 nm Thick SiO₂/Si Substrates: Reflection and Transmission Phase Changes at Interfaces

Cho

et al. 2018

Adv Materials Inter

Advanced Optical Materials

Section: Enhancement Of Absorption In Tmds and Black Phosphorusmentioning

confidence: 99%

Engineering Optical Absorption in Graphene and Other 2D Materials: Advances and Applications

Lü

Gupta

et al. 2019

135

2D materials are promising but remain to be further explored, with respect to their usage in various optoelectronic devices. Generally, 2D materials exhibit far less than ideal absorption due to their thickness, limiting their deployment in practical optoelectronic applications. To address this challenge, extensive research has been performed utilizing different designs, such as distributed Bragg reflector microcavities, metallic reflectors, photonic crystal nanocavities, and plasmonic nanostructures, to confine light within 2D materials and increase light absorption. Recent progresses in enhancing light absorption in graphene and other 2D materials such as transition metal dichalcogenides and phosphorene are reviewed. Some physical mechanisms that realize enhanced absorption in 2D materials, as well as their potential applications are also discussed.

“…İki boyutlu malzemeler fotonikten giyilebilir elektronik uygulamalarına [3] [4] [5] [6] [7], güneş panellerinden lityum iyon bataryalarına [8] [9] kadar birçok alanda kullanılmaktadır. Bu nedenle günümüzde iki boyutlu malzemelerin sentezlenmesini, transferini, ve uygulamalarını konu alan her yıl on binlerce bilimsel yayın yapılmaktadır.…”

Section: Introductionunclassified

İki Boyutlu Malzemelerin Tekstil Yüzeylerine Transferi

Gürarslan¹

2018

J Text Eng

Son yıllarda 2 boyutlu malzemeler üzerinde yapılan çalışmalar büyük bir ilgi uyandırmıştır. Bu çalışmada iki boyutlu malzemelerden birisi olan molibden disülfür (MoS 2 ), kimyasal buhar biriktirme tekniği ile sentezlenerek çeşitli tekstil yüzeylerine transfer edilmiştir. Tekstil yüzeyleri üzerindeki MoS 2 film optik mikroskop, AFM, SEM, ve Raman cihazları kullanılarak karakterize edilmiştir. Bu çalışmanın sonuçları iki boyutlu malzemelerin tekstil yüzeylerine kolayca transfer edilebileceğini göstermektedir. Böylelikle iki boyutlu malzemelerin tekstil mamullerine aplikasyonu ve çeşitli uygulamalarda kullanılmasının önü açılmıştır.