Structural and optical properties of single and bilayer silver and gold films

Yankovskii, Georgiy M.; Komarov, A. V.; Puzko, Roman S.; Baryshev, A. V.; Afanasev, Konstantin; Boginskaya, I. A.; Bykov, I. V.; Merzlikin, A. M.; Rodionov, Ilya A.; Ryzhikov, Ilya A.

doi:10.1134/s1063783416120349

Cited by 18 publications

(10 citation statements)

References 25 publications

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“…Single-crystalline metal thin films should be a proper way to solve described problems, but it is extremely hard to fabricate them with high quality. One of the most challenging metal in terms of single-crystalline growth is silver, because of its natural chemical instability [12,13], high sensitivity to substrate surface reconstruction and impurities, lattice-matched substrate dewetting at elevated growth temperatures [14] and optical properties degradation over time [15]. All the listed above silver film growth issues are in practice the potential sources of films poor optical properties, characterized by a short SPP propagation length.…”

Section: Introductionmentioning

confidence: 99%

Toward a theoretically limited SPP propagation length above two hundred microns on an ultra-smooth silver surface [Invited]

Baburin

Kalmykov

Kirtaev

et al. 2018

Opt. Mater. Express

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Russian Federation 7 baburin@bmstu.ru 8 melentiev@isan.troitsk.ru 9 balykin@isan.troitsk.ru * A.S. Baburin and A.S. Kalmykov are contributed equally to this work.Abstract: We demonstrate the optical medium for surface plasmon -polariton waves (SPP) propagation with ultra low losses corresponding to the theoretically limited values. The unique element of the optical medium is an atomically-flat single-crystalline silver thin film which provides extremely low losses. The SPP excited on the surface of such thin films (λ = 780 nm) is characterized by a SPP propagation length equal to 200 µm, which is twice longer than previously reported experimental results and corresponds to theoretically limited values for silver films.

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Section: Introductionmentioning

confidence: 99%

Toward a theoretically limited SPP propagation length above two hundred microns on an ultra-smooth silver surface [Invited]

Baburin

Kalmykov

Kirtaev

et al. 2018

Opt. Mater. Express

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“…These ε 2 spectrum features can be explained by internal interfaces effects 45 , that is, with the surface roughness and morphology increase the silver surface oxidation and the chemical reactivity is boosting. The observed typical peaks in ε 2 are primarily due to the surface reaction with adsorbed sulphur 32,45 , which transforms the silver into a non-metal silver-sulphide (by transfer of S-ions through the interface). In case of polycrystalline films the surface topography (active surface area) plays the key role in the increased silver surface chemical reactivity leading to ε 2 spectrum degradation close to interband transition threshold.…”

Section: Resultsmentioning

confidence: 99%

“…To quantitatively estimate an influence of substrate crystalline structure on films quality, we additionally deposit the SCULL silver films on widely used silicon (100), silicon (110), and mica substrates. Nominally 35-nm-thick single-crystalline silver films were evaporated using the SCULL process (base pressure 3 × 10 −8 Torr, see Supplementary Information) on different substrates (Table 1), which are the thinnest PVD single-crystalline silver films than those reported previously 18,32,33 . On the other hand, the SCULL process has no fundamental limitations in a thicker film synthesis, which is crucial for applications sensitive to SPP substrate absorption.…”

Section: Introductionmentioning

confidence: 99%

Quantum Engineering of Atomically Smooth Single-Crystalline Silver Films

Rodionov

Baburin

Gabidullin

et al. 2019

Sci Rep

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There is a demand for ultra low-loss metal films with high-quality single crystals and perfect surface for nanophotonics and quantum information processing. Many researches are devoted to alternative materials, but silver is by far theoretically the most preferred low-loss material at optical and near-IR frequencies. Usually, epitaxial growth is used to deposit single-crystalline silver films, but they still suffer from unpredictable losses and well-known dewetting effect that strongly limits films quality. Here we report the two-step approach for e-beam evaporation of atomically smooth single-crystalline metal films. The proposed method is based on the thermodynamic control of film growth kinetics at atomic level, which allows depositing state-of-art metal films and overcoming the film-surface dewetting. Here we use it to deposit 35–100 nm thick single-crystalline silver films with the sub-100pm surface roughness and theoretically limited optical losses, considering an ideal material for ultrahigh-Q nanophotonic devices. Utilizing these films we experimentally estimate the contribution of grain boundaries, material purity, surface roughness and crystallinity to optical properties of metal films. We demonstrate our «SCULL» two-step approach for single-crystalline growth of silver, gold and aluminum films which open fundamentally new possibilities in nanophotonics, biotechnology and superconductive quantum technologies. We believe it could be readily adopted for the synthesis of other extremely low-loss single-crystalline metal films.

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“…However, such films have limited applications due to low thermal conductivity, leading to SERS substrate degradation when exposed to exciting laser radiation power above several mW. By experimentally controlling evaporation process recipe parameters, it becomes possible to obtain continuous noble metal thin films with a well-controlled morphology down to atomically flat surfaces, crystalline structure, electrical and optical parameters [41][42][43][44][45][46][47].…”

Section: Introductionmentioning

confidence: 99%

SERS-Active Substrates Nanoengineering Based on e-Beam Evaporated Self-Assembled Silver Films

et al. 2019

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Surface-enhanced Raman spectroscopy (SERS) has been intensely studied as a possible solution in the fields of analytical chemistry and biosensorics for decades. Substantial research has been devoted to engineering signal enhanced SERS-active substrates based on semi-continuous nanostructured silver and gold films, or agglomerates of micro- and nanoparticles in solution. Herein, we demonstrate the high-amplitude spectra of myoglobin precipitated out of ultra-low concentration solutions (below 10 μg/mL) using e-beam evaporated continuous self-assembled silver films. We observe up to 105 times Raman signal amplification with purposefully designed SERS-active substrates in comparison with the control samples. SERS-active substrates are obtained by electron beam evaporation of silver thin films with well controlled nanostructured surface morphology. The characteristic dimensions of the morphology elements vary in the range from several to tens of nanometers. Using optical confocal microscopy we demonstrate that proteins form a conformation on the surface of the self-assembled silver film, which results in an effective enhancement of giant Raman scattering signal. We investigate the various SERS substrates surface morphologies by means of atomic force microscopy (AFM) in combination with deep data analysis with Gwyddion software and a number of machine learning techniques. Based on these results, we identify the most significant film surface morphology patterns and evaporation recipe parameters to obtain the highest amplitude SERS spectra. Moreover, we demonstrate the possibility of automated selection of suitable morphological parameters to obtain the high-amplitude spectra. The developed AFM data auto-analysis procedures are used for smart optimization of SERS-active substrates nanoengineering processes.

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Structural and optical properties of single and bilayer silver and gold films

Cited by 18 publications

References 25 publications

Toward a theoretically limited SPP propagation length above two hundred microns on an ultra-smooth silver surface [Invited]

Toward a theoretically limited SPP propagation length above two hundred microns on an ultra-smooth silver surface [Invited]

Quantum Engineering of Atomically Smooth Single-Crystalline Silver Films

SERS-Active Substrates Nanoengineering Based on e-Beam Evaporated Self-Assembled Silver Films

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