Topic
Raman spectroscopy
About: Raman spectroscopy is a research topic. Over the lifetime, 122605 publications have been published within this topic receiving 2891083 citations. The topic is also known as: Raman Spectrum Analysis & spectrum Analysis, Raman.
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TL;DR: In this paper, the structural properties of a series of films grown under a variation of the dilution of the process gas silane in hydrogen, which induces a transition from highly crystalline to amorphous growth, were investigated.
Abstract: The growth of microcrystalline silicon prepared by plasma-enhanced chemical vapour deposition depends on the deposition conditions and yields films with variable content of crystalline grains, amorphous network, grain boundaries and voids. The changes in the structural properties of a series of films grown under a variation of the dilution of the process gas silane in hydrogen, which induces a transition from highly crystalline to amorphous growth, were investigated. The evolution of the crystalline volume fraction was quantitatively analysed by Raman spectroscopy and X-ray diffraction. The results confirm the need for proper correction of the Raman data for optical absorption and Raman cross-section. Transmission electron microscopy was used to investigate the characteristics and the variation in the microstructure. Upon increasing the silane concentration the strong columnar growth with narrow grain boundaries degrades towards the growth of small irregularly shaped grains enclosed in an amorpho...
278 citations
TL;DR: The transition from microcrystalline to nanocrystalline diamond films grown from Ar/H2/CH4 microwave plasmas has been investigated in this article, showing that the surface morphology, the grain size, and the growth mechanism of the diamond films depend strongly on the ratio of Ar to H2 in the reactant gases.
Abstract: The transition from microcrystalline to nanocrystalline diamond films grown from Ar/H2/CH4 microwave plasmas has been investigated. Both the cross-section and plan-view micrographs of scanning electron microscopy reveal that the surface morphology, the grain size, and the growth mechanism of the diamond films depend strongly on the ratio of Ar to H2 in the reactant gases. Microcrystalline grain size and columnar growth have been observed from films produced from Ar/H2/CH4 microwave discharges with low concentrations of Ar in the reactant gases. By contrast, the films grown from Ar/H2/CH4 microwave plasmas with a high concentration of Ar in the reactant gases consist of phase pure nanocrystalline diamond, which has been characterized by transmission electron microscopy, selected area electron diffraction, and electron energy loss spectroscopy. X-ray diffraction and Raman spectroscopy reveal that the width of the diffraction peaks and the Raman bands of the as-grown films depends on the ratio of Ar to H2 in...
278 citations
TL;DR: It is shown that insertion of graphene can effectively decouple MoS2 from the perturbations imparted by metal contacts (e.g., strain), while maintaining an effective electronic coupling between metal contact and MoS1, suggesting that graphene can act as a conductive buffer layer in TMD electronics.
Abstract: The understanding of the metal and transition metal dichalcogenide (TMD) interface is critical for future electronic device technologies based on this new class of two-dimensional semiconductors. Here, we investigate the initial growth of nanometer-thick Pd, Au, and Ag films on monolayer MoS2. Distinct growth morphologies are identified by atomic force microscopy: Pd forms a uniform contact, Au clusters into nanostructures, and Ag forms randomly distributed islands on MoS2. The formation of these different interfaces is elucidated by large-scale spin-polarized density functional theory calculations. Using Raman spectroscopy, we find that the interface homogeneity shows characteristic Raman shifts in E2g1 and A1g modes. Interestingly, we show that insertion of graphene between metal and MoS2 can effectively decouple MoS2 from the perturbations imparted by metal contacts (e.g., strain), while maintaining an effective electronic coupling between metal contact and MoS2, suggesting that graphene can act as a c...
277 citations
TL;DR: It is shown that coherent anti-Stokes Raman spectroscopy (CARS) can be used to obtain single-molecule detection sensitivity, by exploiting the unique light harvesting properties of plasmonic Fano resonances.
Abstract: The field enhancements arising in plasmonic nanostructures make them ideal as substrates for molecular sensors. In this study, Zhang et al. achieve single molecule sensitivity with Fano resonances in a quadrumer nanostructure and coherent anti-Stokes Raman spectroscopy.
277 citations
IBM1
TL;DR: Time-dependent spontaneous Raman spectra of optically pumped GaAs have been measured with subpicosecond time resolution and substantial time-dependent changes are observed in the spectra which result from screening of the LO phonons by the free carriers and the relaxation of thefree carriers to the band edges.
Abstract: Time-dependent spontaneous Raman spectra of optically pumped GaAs have been measured with subpicosecond time resolution. When the optically injected carrier density is less than ${10}^{17}$ ${\mathrm{cm}}^{\ensuremath{-}3}$, we temporally resolve the growth of the optically induced nonequilibrium LO-phonon population and deduce an average electron-phonon scattering time of about 165 fs. For higher injected carrier densities, substantial time-dependent changes are observed in the spectra which result from screening of the LO phonons by the free carriers and the relaxation of the free carriers to the band edges.
277 citations