Influence of roughness, porosity and grain morphology on the optical properties of ultrathin Ag films

Ciambriello, Luca; Cavaliere, Emanuele; Gavioli, Luca

doi:10.1016/j.apsusc.2021.151885

Cited by 14 publications

(8 citation statements)

References 47 publications

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“…In the reflection and transmission spectra acquired in the 280–1900 nm wavelength range (Figure a,b, respectively), the ITO/glass substrate shows an oscillating behavior due to interference fringes arising from multiple internal reflections inside the ITO coating. By modeling the substrate as a two-layer system with a 1 mm-thick BK7 glass (with a fixed refractive index from Rosete-Aguilar et al) and a 130 ±5 nm-thick ITO coating layer, the ITO dielectric function was obtained by fitting the experimental data through the DEMON code . The set of oscillators identifying the ITO dielectric function and reported in the Supporting Information (Section S3) was obtained by fitting the ITO/glass experimental R and T data.…”

Section: Resultsmentioning

confidence: 99%

“…Reflection ( R ) and transmission ( T ) spectra have been acquired at normal incidence by a Perkin-Elmer Lambda 950 Spectrometer in the 250–1900 nm range. The optical spectra have been modeled and fitted through the home-made DEMON software by employing a multilayer model with each layer dielectric function being described by Bruggeman’s effective medium approximation (BEMA). The quantity false( R exp − R model false) 2 + false( T exp − T model false) 2 was minimized to refine the parameters in the multilayer model.…”

Section: Methodsmentioning

confidence: 99%

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Role of Electrode Thickness in NiFe Nanogranular Films for Oxygen Evolution Reaction

et al. 2022

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Nanostructured materials may provide a route to overcome the electrode-limiting performance in water splitting, the oxygen evolution reaction (OER), within the framework of low-cost catalysts search. However, for alloyed NiFe nanostructures, the relationship among the OER efficiency and the electrode physical characteristics (morphology, porosity, size, thickness, or mass loading) is largely unknown. This work introduces a new type of alloyed NiFe (90/10% at) nanogranular electrodes obtained by supersonic cluster beam deposition and investigates the dependence of their catalytic activity toward the OER on the film morphological and stoichiometric properties. The synthesized alloyed NiFe nanoparticles with 0.3–3.8 nm size assemble from the gas phase to form ultrathin film electrodes with thickness in the 15–88 nm range, corresponding to 5–30 μg/cm2 mass loading. The fitting of the optical spectroscopic data by an effective medium approximation model suggests that, independent of the thickness, the films have a 20% porosity and are completely hydroxydated. The resulting catalytic efficiency is independent on the film thickness, while the turnover frequency decreases with increasing electrode loading. These data suggest that an excess of catalyst mass with respect to the OER active sites is deposited in the case of thicker electrodes and sets the 15 nm film as an upper loading limit to maximize the electrocatalyst efficiency. This study represents a crucial step toward thickness optimization of NiFe electrodes to fabricate low-cost OER catalysts.

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Section: Resultsmentioning

confidence: 99%

Section: Methodsmentioning

confidence: 99%

Role of Electrode Thickness in NiFe Nanogranular Films for Oxygen Evolution Reaction

et al. 2022

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“…Consequently, once the gold layer is initiated, the optical and thermal properties change to a composite structure where the growing gold layer is optically in series with the AuC x core material relative to the laser flux and is thermally in parallel relative to the substrate heat sink. While a concentric bi-layer model using gold surrounding an AuC x core was explored, the optical absorption below ~50 nm is very sensitive to the surface roughness [ 52 ], which significantly enhances the optical absorption. Using standard gold properties has the effect of significantly reducing the structure temperature below the decomposition temperature, primarily due to significant reflectance but also due to enhanced thermal conduction (see SI-3 for an example and model details).…”

Section: Resultsmentioning

confidence: 99%

Selected Area Deposition of High Purity Gold for Functional 3D Architectures

2023

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Selected area deposition of high purity gold films onto nanoscale 3D architectures is highly desirable as gold is conductive, inert, plasmonically active, and can be functionalized with thiol chemistries, which are useful in many biological applications. Here, we show that high-purity gold coatings can be selectively grown with the Me2Au (acac) precursor onto nanoscale 3D architectures via a pulsed laser pyrolytic chemical vapor deposition process. The selected area of deposition is achieved due to the high thermal resistance of the nanoscale geometries. Focused electron beam induced deposits (FEBID) and carbon nanofibers are functionalized with gold coatings, and we demonstrate the effects that laser irradiance, pulse width, and precursor pressure have on the growth rate. Furthermore, we demonstrate selected area deposition with a feature-targeting resolutions of ~100 and 5 µm, using diode lasers coupled to a multimode (915 nm) and single mode (785 nm) fiber optic, respectively. The experimental results are rationalized via finite element thermal modeling.

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“…31,32 The properties of Ag thin films generally depend on thickness. 33 Increasing the film thickness induces a rougher surface structure than that of thinner films, and rough surfaces cause optical loss from the scattering of light. Therefore, thin silver films are expected to improve the photoresponse of photodetectors.…”

Section: Introductionmentioning

confidence: 99%

“…However, gold is an expensive material, and copper is easily oxidized in the atmosphere. Therefore, among these materials, silver thin films are appropriate for electrodes in optoelectronics and are widely used. , The properties of Ag thin films generally depend on thickness . Increasing the film thickness induces a rougher surface structure than that of thinner films, and rough surfaces cause optical loss from the scattering of light.…”

Section: Introductionmentioning

confidence: 99%

Ag₂O/β-Ga₂O₃ Heterojunction-Based Self-Powered Solar Blind Photodetector with High Responsivity and Stability

Park

et al. 2022

ACS Appl. Mater. Interfaces

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Self-powered deep-ultraviolet photodetectors have received considerable attention in recent years because of their efficiency, reliability, and various applications in civilian and military fields. Herein, a Ag/Ag 2 O layer is continuously deposited on a β-Ga 2 O 3 epitaxial layer by a facing target sputtering system without opening the chamber, which has an advantage in time and cost. A p−n junction photodetector was constructed through the Ag 2 O/β-Ga 2 O 3 heterojunction and by varying the thickness of the Ag film, which was controlled by the sputtering time. The effect of top electrode thickness on the photoresponse characteristics of photodetectors was studied. Because thin Ag films have low surface roughness, indicating low optical loss and good interfacial conditions, photodetectors using a thin Ag film as the top electrode exhibit high photoresponsivity. However, Ag films that were thinner than the threshold thickness, which is the minimum thickness required to form a continuous, homogeneous surface film, exhibited rather low performance owing to the high reflection and scattering caused by the inhomogeneous surface morphology. The as-fabricated photodetector with a 20 nm Ag film presents a high on/off ratio of 3.43 × 10 8 , responsivity and detectivity of 25.65 mA/W and 6.10 × 10 11 Jones, respectively, and comparable rise and decay times of 108 and 80 ms, respectively. Additionally, even after three months of storage in an ambient environment, the photoresponse of the photodetector was maintained, indicating good stability in air. These results suggest that Ag 2 O/β-Ga 2 O 3 heterojunction-based photodetectors with thin Ag films can be used in various applications requiring deep-ultraviolet detection without an external power supply. KEYWORDS: deep ultraviolet (DUV), photodetector, self-powered, Ag film thickness, Ag 2 O/β-Ga 2 O 3 , p−n junction

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Influence of roughness, porosity and grain morphology on the optical properties of ultrathin Ag films

Cited by 14 publications

References 47 publications

Role of Electrode Thickness in NiFe Nanogranular Films for Oxygen Evolution Reaction

Role of Electrode Thickness in NiFe Nanogranular Films for Oxygen Evolution Reaction

Selected Area Deposition of High Purity Gold for Functional 3D Architectures

Ag₂O/β-Ga₂O₃ Heterojunction-Based Self-Powered Solar Blind Photodetector with High Responsivity and Stability

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Influence of roughness, porosity and grain morphology on the optical properties of ultrathin Ag films

Cited by 14 publications

References 47 publications

Role of Electrode Thickness in NiFe Nanogranular Films for Oxygen Evolution Reaction

Role of Electrode Thickness in NiFe Nanogranular Films for Oxygen Evolution Reaction

Selected Area Deposition of High Purity Gold for Functional 3D Architectures

Ag2O/β-Ga2O3 Heterojunction-Based Self-Powered Solar Blind Photodetector with High Responsivity and Stability

Contact Info

Product

Resources

About

Ag₂O/β-Ga₂O₃ Heterojunction-Based Self-Powered Solar Blind Photodetector with High Responsivity and Stability