Surface-enhanced Raman scattering of suspended monolayer graphene

Huang, Cheng; Lin, Bing Jie; Lin, Hsing Ying; Shih, Fu Yu; Wang, Wei Hua; Liu, Chih Yi; Chui, Hsiang‐Chen

doi:10.1186/1556-276x-8-480

Cited by 16 publications

(8 citation statements)

References 39 publications

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“…This phenomenon agrees with the surface limited diffusion [34,35,36,37]. This process can be attributed to the variation of the surface diffusion coefficient with temperature [40]. Due to the differences in the chemical potentials among the Ag nanoislands, the smaller nanoislands are thermodynamically unstable and they dissolve in atoms for each fixed temperature [41].…”

Section: Resultssupporting

confidence: 66%

Fast Hydrogenation and Dehydrogenation of Pt/Pd Bimetal Decorated over Nano-Structured Ag Islands Grown on Alumina Substrates

Rahaman

Yaqoob

Kim

2018

Sensors

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This study reports the fast hydrogenation and dehydrogenation of ultra-thin discrete platinum/palladium (Pt/Pd) bimetal over nano-structured Ag islands grown on rough alumina substrate by a RF magnetron sputtering technique. The morphology of Ag nanoislands was optimized by RF magnetron sputtering and rapid thermal annealing process. Later, Pt/Pd bimetal (10/10) nm were deposited by RF magnetron sputtering on the nanostructured Ag islands. After the surface morphological optimization of Ag nanoislands, the resultant structure Pt/Pd@Ag nanoislands at alumina substrate showed a fast and enhanced hydrogenation and dehydrogenation (20/25 s), response magnitude of 2.3% (10,000 ppm), and a broad detection range of 500 to 40,000 ppm at the operating temperature of 120 °C. The superior hydrogenation and dehydrogenation features can be attributed to the hydrogen induced changes in the work function of Pt/Pd bimetal which enhances the coulomb scattering of percolated Pt/Pd@Ag nanoislands. More importantly, the atomic arrangements and synergetic effects of complex metal alloy interfacial structure on Ag nanoislands, supported by rough alumina substrate incorporate the vital role in accelerating the H2 absorption and desorption properties.

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Section: Resultssupporting

confidence: 66%

Fast Hydrogenation and Dehydrogenation of Pt/Pd Bimetal Decorated over Nano-Structured Ag Islands Grown on Alumina Substrates

Rahaman

Yaqoob

Kim

2018

Sensors

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“…Moreover, with the increase of temperature, small particles are lessened and the value distribution of AgNIs diameter became more concentrated, which indicated that the substrate becomes more uniform. The changes in the AgNIs morphologies at different temperatures are completed via surface-limited diffusion 25 , 26 , which is analogous to ostwald ripening. This process can be attributed to the varying of surface diffusion coefficient with temperature 27 .…”

Section: Resultsmentioning

confidence: 98%

A study on the correlation between the dewetting temperature of Ag film and SERS intensity

Quan

Zhang

et al. 2017

Sci Rep

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The thermally dewetted metal nano-islands have been actively investigated as cost-effective SERS-active substrates with a large area, good reproducibility and repeatability via simple fabrication process. However, the correlation between the dewetting temperature of metal film and SERS intensity hasn’t been systematically studied. In this work, taking Ag nano-islands (AgNIs) as an example, we reported a strategy to investigate the correlation between the dewetting temperature of metal film and SERS intensity. We described the morphology evolution of AgNIs on the SiO2 planar substrate in different temperatures and got the quantitative information in surface-limited diffusion process (SLDP) as a function of annealing temperature via classical mean-field nucleation theory. Those functions were further used in the simulation of electromagnetic field to obtain the correlation between the dewetting temperature of Ag film and theoretical analysis. In addition, Raman mapping was done on samples annealed at different temperatures, with R6G as an analyte, to accomplish the analysis of the correlation between the dewetting temperature of Ag film and SERS intensity, which is consistent with the theoretical analysis. For SLDP, we used the morphological characterization of five samples prepared by different annealing temperatures to successfully illustrate the change in SERS intensity with the temperature fluctuation, obtaining a small deviation between the experimental results and theoretic prediction.

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“…Table compares the characteristics of the enhancement technique in this study with those of other techniques reported previously. Although the Raman/PL signals of 2D materials have been enhanced significantly in previous studies when using plasmonic nanostructures − and photonic crystal cavities, − several external disturbances (e.g., peak shifting, peak distortion) would arise, making characterization with these techniques difficult. In contrast, the thin film-based interference enhancement method appears be a superior method for increasing the light outcoupling of 2D materials because the high enhancement effect occurs without affecting the spectral properties.…”

Section: Resultsmentioning

confidence: 99%

“…Therefore, enhancing the Raman and PL signals, in other words, the light outcoupling, of 2D materials has become particularly important for detailed analyses of their fine structural characteristics. Although several techniques have been developed previously to increase the Raman or PL signals of 2D materials, − they usually disturb the external properties of the 2D materials in an unpredictable manner, making it difficult to characterize the original Raman or PL spectra. In addition, simple approaches toward enhancing both the Raman and PL emissions of a range of 2D materials have not been reported previously.…”

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confidence: 99%

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Single Type of Nanocavity Structure Enhances Light Outcouplings from Various Two-Dimensional Materials by over 100-Fold

2016

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In this study we developed a method, using a simple two-layer nanocavity structure, to significantly enhance light outcoupling from two-dimensional (2D) materials. Because the surface electric fields (E-fields) of the nanocavities were enhanced greatly over ultrabroadband regimes, the excitation of various 2D materials with laser light and their Raman and photoluminescence (PL) light emissions were all enhanced dramatically while maintaining band-to-band ratios and peak positions precisely. At the same time, the optical visibility of the 2D materials was also enhanced significantly over a broad spectral regime. Using a single type of Ag/SiO2 nanocavity structure, we obtained a 475-fold, equal enhancement in the intensities of the main Raman peaks of single-layer graphene (SLG) and more than a 350-fold increase in the intensities of both the Raman and PL signals of single-layer tungsten disulfide (WS2). Notably, the light outcouplings of these 2D materials were enhanced dramatically without any spectral distortion generated by the nanocavity. Moreover, a nanocavity structure prepared from a nonplasmonic metal reflector also enhanced the light outcoupling from 2D materials by over 200-fold. Combined with Raman and PL spectroscopy, such simple nanocavity structures appear to have great applicability for precise and reliable investigations, providing abundant structural information, of a variety of 2D materials.

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Surface-enhanced Raman scattering of suspended monolayer graphene

Cited by 16 publications

References 39 publications

Fast Hydrogenation and Dehydrogenation of Pt/Pd Bimetal Decorated over Nano-Structured Ag Islands Grown on Alumina Substrates

Fast Hydrogenation and Dehydrogenation of Pt/Pd Bimetal Decorated over Nano-Structured Ag Islands Grown on Alumina Substrates

A study on the correlation between the dewetting temperature of Ag film and SERS intensity

Single Type of Nanocavity Structure Enhances Light Outcouplings from Various Two-Dimensional Materials by over 100-Fold

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