Interference effect on Raman spectrum of graphene on<mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" display="inline"><mml:mrow><mml:msub><mml:mrow><mml:mtext>SiO</mml:mtext></mml:mrow><mml:mn>2</mml:mn></mml:msub><mml:mo>/</mml:mo><mml:mtext>Si</mml:mtext></mml:mrow></mml:math>

Yoon, Duhee; Moon, Hyerim; Son, Young Kap; Choi, Jin Sik; Park, Bae Ho; Hun, Young; Kim, Young Dong; Cheong, Hyeonsik

doi:10.1103/physrevb.80.125422

Cited by 288 publications

(229 citation statements)

References 37 publications

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“…Graphene on hBN is closest to the undoped region of the plot, followed by OTS, SiO 2 , and finally Al 2 O 3 at the more highly doped region. (Although the peak intensities on Al 2 O 3 have not been corrected for optical interference effects from the different substrate, 42 the peak positions are accurate.) After diazonium functionalization, the data points from all substrates move further along the doping trend line.…”

Section: Analysis Of Raman Spectroscopic Mapsmentioning

confidence: 99%

Understanding and controlling the substrate effect on graphene electron-transfer chemistry via reactivity imprint lithography

et al. 2012

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The chemical functionalization of graphene enables control over electronic properties and sensor recognition sites. However, its study is confounded by an unusually strong influence of the underlying substrate. In this paper, we show a stark difference in the rate of electron transfer chemistry with aryl diazonium salts on monolayer graphene supported on a broad range of substrates. Reactions proceed rapidly when graphene is on SiO 2 and Al 2 O 3 (sapphire), but negligibly on alkyl-terminated and hexagonal boron nitride (hBN) surfaces. The effect is contrary to expectations based on doping levels and can instead be described using a reactivity model accounting for substrate-induced electron-hole puddles in graphene. Raman spectroscopic mapping is used to characterize the effect of the substrates on graphene. Reactivity imprint lithography (RIL) is demonstrated as a technique for spatially patterning chemicalgroups on graphene by patterning the underlying substrate, and is applied to the covalent tethering of proteins on graphene.

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Section: Analysis Of Raman Spectroscopic Mapsmentioning

confidence: 99%

Understanding and controlling the substrate effect on graphene electron-transfer chemistry via reactivity imprint lithography

et al. 2012

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“…First, it provides some interference-based enhancement in the SLG absorption [84][85][86][87]. Fig.12a plots the exposed SLG absorption for the system described in Fig.1 on top of a 300nm SiO 2 /Si substrate.…”

Section: Sio2/si Substrate Effectsmentioning

confidence: 99%

Surface Plasmon Polariton Graphene Photodetectors

et al. 2015

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The combination of plasmonic nanoparticles and graphene enhances the responsivity and spectral selectivity of graphene-based photodetectors. However, the small area of the metal-graphene junction, where the induced electron-hole pairs separate, limits the photoactive region to sub-micron length scales. Here, we couple graphene with a plasmonic grating and exploit the resulting surface plasmon polaritons to deliver the collected photons to the junction region of a metal-graphenemetal photodetector. This results into a 400% enhancement of responsivity and a 1000% increase in photoactive length, combined with tunable spectral selectivity. The interference between surface plasmon polaritons and the incident wave introduces new functionalities, such as light flux attraction or repulsion from the contact edges, enabling the tailored design of the photodetector's spectral response. This architecture can also be used for surface plasmon bio-sensing with direct-electricreadout, eliminating the need of complicated optics.Graphene-based photodetectors (PDs) [1,2] have been reported with ultra-fast operating speeds (up to 262GHz from the measured intrinsic response time of graphene carriers [3]) and broadband operation from the visible and infrared [3][4][5][6][7][8][9][10][11][12][13][14][15][16] up to the THz [17][18][19]. The simplest graphene-based photodetection scheme relies on the metal-graphene-metal (MGM) architecture [5,7,8,11,[20][21][22], where the photoresponse is due to a combination of photo-thermoelectric and photovoltaic effects [5,7,8,11,[20][21][22]. For both mechanisms, the presence of a junction is required to spatially separate excited electronhole (e-h) pairs [5,7,8,11,[20][21][22]. At the metal-graphene junction, a work-function difference causes charge transfer and a shift of the graphene Fermi level underneath the contact [4,5,7,23], compared to that of graphene away from the contact [4,5,7,23], resulting into a build-up of an internal electric field (photovoltaic mechanism) [5,7,24,25] and into a difference of Seebeck coefficients (photo-thermoelectric mechanism) [11,21,26]. An alternative way to create a junction is to use a set of gate electrodes to electrostatically dope graphene [8,11].

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“…[10][11][12][13][14][15][16] Nevertheless, most techniques rely on the specific properties of 2D materials. For example, one can identify the layer number, denoted as N, of MoS 2 by the intensity or peak positions of the corresponding photoluminescence (PL) peak and Raman modes.…”

mentioning

confidence: 99%

“…However, the alloy flakes with the same layer number exhibit the C modes with almost the same frequency, in spite of the significant peak intensity due to the optical interference effect in the MoWS 2 /SiO 2 /Si multilayer. 13,16 Alloy flakes with different layer number display disparate C modes, offering a reliable diagnostic of the layer number. Similar behavior has also been observed for the LB modes (not shown here).…”

mentioning

confidence: 99%

Substrate-free layer-number identification of two-dimensional materials: A case of Mo0.5W0.5S2 alloy

Qiao

Zhang

et al. 2015

Applied Physics Letters

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Any of two or more two-dimensional (2D) materials with similar properties can be alloyed into a new layered material, namely, 2D alloy. Individual monolayer in 2D alloys are kept together by Van der Waals interactions. The property of multilayer alloys is a function of their layer number. Here, we studied the shear (C) and layerbreathing (LB) modes of Mo 0.5 W 0.5 S 2 alloy flakes and their link to the layer number of alloy flakes. The study reveals that the disorder effect is absent in the C and LB modes of 2D alloys, and the monatomic chain model can be used to estimate the frequencies of the C and LB modes. We demonstrated how to use the C and LB mode frequency to identify the layer number of alloy flakes deposited on different substrates. This technique is independent of the substrate, stoichiometry, monolayer thickness and complex refractive index of 2D materials, offering a robust and substrate-free approach for layer-number identification of 2D materials. [6][7][8][9] The 2D alloys are a rich source of 2D materials because they can exhibit tunable properties because the ratio of two end compositions can be controllable. 6,9 The key to form a good quality of 2D monolayer is mixing the end compositions at atomic scale. Individual monolayers in the 2D alloys are kept together by Van der Waals interations. Similar to graphite and graphene, the property of multilayer alloys is a function of their layer number. How to determine the layer number of ultrathin 2D alloys is thus of primary importance for fundamental science and applications.Several optical techniques have been developed to identify the layer number of 2D materials. [10][11][12][13][14][15][16] Nevertheless, most techniques rely on the specific properties of 2D materials. For example, one can identify the layer number, denoted as N, of MoS 2 by the intensity or peak positions of the corresponding photoluminescence (PL) peak and Raman modes. 14,15 The mostly used technique is based upon optical contrast of 2D materials against dielectric substrates, such as a Si substrate covered with a SiO 2 layers. 10,12 To precisely identify N of few-layer 2D materials, the experimental optical contrast must be compared with the theoretical one for different N. However, the theoretical calculations require predetermined parameters, including thickness of a single layer, complex refractive index of the material and information of the substrate, 11,17 which poses great challenge for research on new 2D materials in early stage. Therefore, it is desirable to develop a novel approach to identify the layer number of fewlayer 2D materials, relying on as little prerequisite parameters as possible.The interlayer modes of multilayer 2D materials originates from the relative motions of the rigid monolayer planes themselves, either perpendicular or parallel to their normal, such as the shear (C) modes and the layer breathing (LB) modes. [18][19][20][21][22][23][24] The C and LB modes are the collective vibration modes of all the layers so their frequency (ω C and ω LB ) depe...

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Interference effect on Raman spectrum of graphene onSiO2/Si

Cited by 288 publications

References 37 publications

Understanding and controlling the substrate effect on graphene electron-transfer chemistry via reactivity imprint lithography

Understanding and controlling the substrate effect on graphene electron-transfer chemistry via reactivity imprint lithography

Surface Plasmon Polariton Graphene Photodetectors

Substrate-free layer-number identification of two-dimensional materials: A case of Mo0.5W0.5S2 alloy

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