Showing papers on "Ellipsometry published in 2017"
TL;DR: It is demonstrated that the direct optical gap of single crystals is dominated by a strongly bound exciton rising over the continuum of indirect interband transitions, revealing the existence of strongly boundexcitons in single crystals and nanoparticles.
Abstract: Anatase TiO2 is among the most studied materials for light-energy conversion applications, but the nature of its fundamental charge excitations is still unknown. Yet it is crucial to establish whether light absorption creates uncorrelated electron-hole pairs or bound excitons and, in the latter case, to determine their character. Here, by combining steady-state angle-resolved photoemission spectroscopy and spectroscopic ellipsometry with state-of-the-art ab initio calculations, we demonstrate that the direct optical gap of single crystals is dominated by a strongly bound exciton rising over the continuum of indirect interband transitions. This exciton possesses an intermediate character between the Wannier-Mott and Frenkel regimes and displays a peculiar two-dimensional wavefunction in the three-dimensional lattice. The nature of the higher-energy excitations is also identified. The universal validity of our results is confirmed up to room temperature by observing the same elementary excitations in defect-rich samples (doped single crystals and nanoparticles) via ultrafast two-dimensional deep-ultraviolet spectroscopy.Here the authors combine steady-state angle-resolved photoemission spectroscopy, ellipsometry and ultrafast two-dimensional ultraviolet spectroscopy to examine the role of many-body correlations in anatase TiO2, revealing the existence of strongly bound excitons in single crystals and nanoparticles.
152 citations
TL;DR: In this article, epitaxial, ultrathin (<10 nm) films of plasmonic TiN are grown on MgO using DC reactive magnetron sputtering, and optical properties of the films are studied through variable angle spectroscopic ellipsometry and Hall measurements.
Abstract: Overcoming the challenge of growing ultrathin metallic films is of great importance for practical applications of nanoplasmonic structures In the present work, epitaxial, ultrathin (<10 nm) films of plasmonic TiN are grown on MgO using DC reactive magnetron sputtering The optical properties of the films are studied through variable angle spectroscopic ellipsometry and Hall measurements As the film thickness decreases, they become less metallic and exhibit higher loss while still remaining plasmonic in the optical range These trends are related to the decreasing carrier concentration in the thinner films and increased scattering, respectively However, all films tested (2, 4, 6, 8, and 10 nm) still remain highly metallic with a carrier concentration on the order of 1022 cm−3 Based on the relationship between the plasma frequency, carrier concentration, and effective mass, it is determined that the reduction in carrier concentration plays the main role in defining the film's optical properties, as variations in the effective mass are found to be minimal for thicknesses above 4 nm However, for the 2 nm film and below, theoretical calculations begin to deviate from experimental values
102 citations
TL;DR: In this paper, the authors performed in-situ high-temperature ellipsometry to quantify the permittivity of TiN films from room temperature to 1258°C and found that the material becomes more absorptive at higher temperatures but maintains its metallic character throughout visible and near infrared frequencies.
Abstract: The refractory metal titanium nitride is promising for high-temperature nanophotonic and plasmonic applications, but its optical properties have not been studied at temperatures exceeding 400 °C. Here, we perform in-situ high-temperature ellipsometry to quantify the permittivity of TiN films from room temperature to 1258 °C. We find that the material becomes more absorptive at higher temperatures but maintains its metallic character throughout visible and near infrared frequencies. X-ray diffraction, atomic force microscopy, and mass spectrometry confirm that TiN retains its bulk crystal quality and that thermal cycling increases the surface roughness, reduces the lattice constant, and reduces the carbon and oxygen contaminant concentrations. The changes in the optical properties of the material are highly reproducible upon repeated heating and cooling, and the room-temperature properties are fully recoverable after cooling. Using the measured high-temperature permittivity, we compute the emissivity, surf...
80 citations
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TL;DR: In this article, the temperature dependent dielectric functions of TiN thin films of varying thicknesses in the technologically relevant visible and near-infrared wavelength range from 330 nm to 2000 nm for temperatures up to 900 0C using in-situ high temperature ellipsometry.
Abstract: Due to their exceptional plasmonic properties, noble metals such as gold and silver have been the materials of choice for the demonstration of various plasmonic and nanophotonic phenomena. However, noble metals' softness, lack of tailorability and low melting point along with challenges in thin film fabrication and device integration have prevented the realization of real-life plasmonic this http URL the recent years, titanium nitride (TiN) has emerged as a promising plasmonic material with good metallic and refractory (high temperature stable) properties. The refractory nature of TiN could enable practical plasmonic devices operating at elevated temperatures for energy conversion and harsh-environment industries such as gas and oil. Here we report on the temperature dependent dielectric functions of TiN thin films of varying thicknesses in the technologically relevant visible and near-infrared wavelength range from 330 nm to 2000 nm for temperatures up to 900 0C using in-situ high temperature ellipsometry. Our findings show that the complex dielectric function of TiN at elevated temperatures deviates from the optical parameters at room temperature, indicating degradation in plasmonic properties both in the real and imaginary parts of the dielectric constant. However, quite strikingly, the relative changes of the optical properties of TiN are significantly smaller compared to its noble metal counterparts. Using simulations, we demonstrate that incorporating the temperature-induced deviations into the numerical models leads to significant differences in the optical responses of high temperature nanophotonic systems. These studies hold the key for accurate modeling of high temperature TiN based optical elements and nanophotonic systems for energy conversion, harsh-environment sensors and heat-assisted applications.
78 citations
TL;DR: In this paper, the in situ high temperature ellipsometry measurements of ultrasmooth and epitaxial quality crystalline films, along with electron beam evaporated polycrystalline silver films at temperatures up to 700 °C, in the wavelength range of 330-2000 nm.
Abstract: Silver holds a unique place in plasmonics compared to other noble metals owing to its low losses in the visible and near-IR wavelength ranges. With a growing interest in local heating and high temperature applications of plasmonics, it is becoming critical to characterize the dielectric function of nanometer-scale thin silver films at higher temperatures, especially near the breakdown temperature, which depends on the film thickness and crystallinity. So far, such a comprehensive study has been missing. Here we report the in situ high temperature ellipsometry measurements of ultrasmooth and epitaxial quality crystalline silver films, along with electron beam evaporated polycrystalline silver films at temperatures up to 700 °C, in the wavelength range of 330–2000 nm. Our findings show that the dielectric function of all the films changes remarkably at elevated temperatures with larger relative changes observed in polycrystalline films. In addition, low-loss epitaxial films were found to be thermally more s...
64 citations
TL;DR: TiO2 nanocolloids prepared by polyol reduction method were successfully used as coating thin films onto borosilicate glass substrates via adsorptive self-assembly process to minimize soiling effect on photovoltaic modules.
Abstract: Transparent titania coatings have self-cleaning and anti-reflection properties (AR) that are of great importance to minimize soiling effect on photovoltaic modules. In this work, TiO2 nanocolloids prepared by polyol reduction method were successfully used as coating thin films onto borosilicate glass substrates via adsorptive self-assembly process. The nanocolloids were characterized by transmission electron microscopy and x-ray diffraction. The average particle size was around 2.6 nm. The films which have an average thickness of 76.2 nm and refractive index of 1.51 showed distinctive anti soiling properties under desert environment. The film surface topography, uniformity, wettability, thickness and refractive index were characterized using x-ray diffraction, atomic force microscopy, scanning electron microscopy, water contact angle measurements and ellipsometry. The self-cleaning properties were investigated by optical microscopy and UV-Vis spectroscopy. The optical images show 56% reduction of dust deposition rate over the coated surfaces compared with bare glass substrates after 7 days of soiling. The transmission optical spectra of these films collected at normal incidence angle show high anti-reflection properties with the coated substrates having transmission loss of less than 6% compared to bare clean glass.
57 citations
20 Mar 2017
TL;DR: This article provides useful design rules for the synthesis of high-quality VO2 thin films by APCVD by optimizing the reaction between VCl4 and ethyl acetate via atmospheric-pressure chemical vapor deposition.
Abstract: Monoclinic vanadium(IV) oxide (VO2) has been widely studied for energy-efficient glazing applications because of its thermochromic properties, displaying a large change in transmission of near-IR wavelengths between the hot and cold states. The optimization of the reaction between VCl4 and ethyl acetate via atmospheric-pressure chemical vapor deposition (APCVD) was shown to produce thin films of monoclinic VO2 with excellent thermochromic properties (ΔTsol = 12%). The tailoring of the thermochromic and visible light transmission was shown to be possible by altering the density and morphology of the deposited films. The films were characterized by X-ray diffraction, atomic-force microscopy, scanning electron microscopy, ellipsometry, and UV–vis spectrometry. This article provides useful design rules for the synthesis of high-quality VO2 thin films by APCVD.
55 citations
TL;DR: In this paper, a detailed optical analysis of semitransparent and opaque planar CH3NH3PbI3 solar cells is reported using a combination of variable-angle spectroscopic ellipsometry and spectrophotometry data, taking the underlying layer stack explicitly into account.
Abstract: Organometal halide perovskites are attracting strong interest as light-harvesting absorber materials in single- and multijunction solar cells. In order to advance the technology, careful optical design of the device architecture and elaborate analysis of optical losses are essential. In this work, a detailed optical analysis of semitransparent and opaque planar CH3NH3PbI3 solar cells is reported. Using a combination of variable-angle spectroscopic ellipsometry and spectrophotometry data, the complex refractive indices of all involved materials in the device architecture are accurately determined, taking the underlying layer stack explicitly into account. The optical properties of partial and complete layer stacks of solar cells, comprising CH3NH3PbI3 films with different CH3NH3PbI3 surface topography roughnesses, are simulated using the transfer-matrix method. Very good agreement between simulated and experimental data is demonstrated. Sub-bandgap absorption is observed in CH3NH3PbI3 layer stacks, which is by means of a ray-tracing model shown to be related to diffuse scattering at the multicrystalline CH3NH3PbI3/air interface. Finally, the optical losses of all layers are discriminated for opaque and semitransparent CH3NH3PbI3 solar cells and four-terminal perovskite/Si tandem solar cells.
55 citations
TL;DR: It is demonstrated that ultra-thin films have lower fragility compared to bulk films, and, when cooled at slow cooling rates, exhibit extreme broadening of the dynamics and eventually complete decoupling between the free surface and substrate regions to produce films with two distinct Tg's.
Abstract: In this report, we use ellipsometry to characterize the glass transition in ultra-thin films of poly(2-vinyl pyridine) (P2VP) supported on a silicon substrate. P2VP is known to have attractive substrate interactions, which can increase the Tg of ultra-thin films compared to the bulk value. Here, we use an extended temperature range to show that the glass transition can be extremely broad, indicating that a large gradient of the dynamics exists through the film with slow dynamics near the substrate and enhanced dynamics at the free surface. To observe the effect of these two interfaces on the average thin film dynamics, cooling rate-dependent Tg (CR-Tg) measurements were used to indirectly probe the average relaxation times of the films. We demonstrate that ultra-thin films have lower fragility compared to bulk films, and, when cooled at slow cooling rates ( 50 K).
54 citations
TL;DR: In this article, the structures of Bi 2 O 3 and NiO thin films were analyzed by X-ray diffraction (XRD) analyses and scanning electron microscopy (SEM).
53 citations
11 Jan 2017
TL;DR: In this paper, the structural, interfacial, optical, and transport properties of large-area MoS2 ultra-thin films on BN-buffered silicon substrates fabricated using magnetron sputtering are investigated.
Abstract: Structural, interfacial, optical, and transport properties of large-area MoS2 ultra-thin films on BN-buffered silicon substrates fabricated using magnetron sputtering are investigated. A relatively simple growth strategy is demonstrated here that simultaneously promotes superior interfacial and bulk MoS2 properties. Few layers of MoS2 are established using x-ray reflectivity, diffraction, ellipsometry, and Raman spectroscopy measurements. Layer-specific modeling of optical constants show very good agreement with first-principles calculations. Conductivity measurements reveal that few-layer MoS2 films are more conducting than many-layer films. Photo-conductivity measurements reveal that the sputter deposited MoS2 films compare favorably with other large-area methods. Our work illustrates that sputtering is a viable route for large-area device applications using transition metal dichalcogenides.
TL;DR: An efficient low temperature plasma enhanced atomic layer deposition (PEALD) process for gallium oxide (Ga2O3) thin films using hexakis(dimethylamido)digallium [Ga(NMe2)3]2 with oxygen (O2) plasma on Si(100) was described.
Abstract: Herein we describe an efficient low temperature (60-160 °C) plasma enhanced atomic layer deposition (PEALD) process for gallium oxide (Ga2O3) thin films using hexakis(dimethylamido)digallium [Ga(NMe2)3]2 with oxygen (O2) plasma on Si(100). The use of O2 plasma was found to have a significant improvement on the growth rate and deposition temperature when compared to former Ga2O3 processes. The process yielded the second highest growth rates (1.5 A per cycle) in terms of Ga2O3 ALD and the lowest temperature to date for the ALD growth of Ga2O3 and typical ALD characteristics were determined. From in situ quartz crystal microbalance (QCM) studies and ex situ ellipsometry measurements, it was deduced that the process is initially substrate-inhibited. Complementary analytical techniques were employed to investigate the crystallinity (grazing-incidence X-ray diffraction), composition (Rutherford backscattering analysis/nuclear reaction analysis/X-ray photoelectron spectroscopy), morphology (X-ray reflectivity/atomic force microscopy) which revealed the formation of amorphous, homogeneous and nearly stoichiometric Ga2O3 thin films of high purity (carbon and nitrogen <2 at.%) under optimised process conditions. Tauc plots obtained via UV-Vis spectroscopy yielded a band gap of 4.9 eV and the transmittance values were more than 80%. Upon annealing at 1000 °C, the transformation to oxygen rich polycrystalline β-gallium oxide took place, which also resulted in the densification and roughening of the layer, accompanied by a slight reduction in the band gap. This work outlines a fast and efficient method for the low temperature ALD growth of Ga2O3 thin films and provides the means to deposit Ga2O3 upon thermally sensitive polymers like polyethylene terephthalate.
TL;DR: A series expansion of the ellipsometric ratio ρ to the second order of the layer thickness relative to the wavelength reveals the first and second ellipsoidal moment, which enables to determine simultaneously both thickness and refractive index of ultra-thin films down to 5 nm thickness.
Abstract: Ellipsometric measurements give information on two film properties with high precision, thickness and refractive index. In the simplest case, the substrate is covered with a single homogenous, transparent film. Yet, with ellipsometry, it is only possible to determine the two film properties thickness and refractive simultaneously if the layer thickness exceeds 15 nm - a restriction well known for a century. Here we present a technique to cross this limitation: A series expansion of the ellipsometric ratio ρ to the second order of the layer thickness relative to the wavelength reveals the first and second ellipsometric moment. These moments are properties of the thin film and independent of incident angle. Using both moments and one additional reference measurement enables to determine simultaneously both thickness and refractive index of ultra-thin films down to 5 nm thickness.
TL;DR: In this paper, the synthesis of nanocomposite thin films on wood surfaces via a one-step process in an atmospheric pressure dielectric barrier discharge (DBD) was examined.
Abstract: This work examines the synthesis of nanocomposite thin films on wood (sugar maple, Acer saccharum , Marsh) surfaces via a one-step process in an atmospheric pressure dielectric barrier discharge (DBD). More specifically, ZnO-SiO 2 nanocomposite coatings are obtained from the atomization in the DBD reactor operated in N 2 /N 2 O (Townsend discharge) of a stable colloidal suspension. This suspension is made of crystalline ZnO nanoparticles (NPs) dispersed in hexamethyldisiloxane (HMDSO) and pentane (Pe). Scanning electron microscopy (SEM) combined with energy dispersive X-ray spectroscopy (EDS) show ZnO agglomerates well embedded into a dense SiO 2 matrix. The chemical composition and the thickness of the matrix is analyzed through Fourier transform infrared spectroscopy (FT-IR) coupled to ellipsometry measurements. SEM further reveals a lumpy morphology; a feature ascribed to the intrinsic roughness of the wood samples.
TL;DR: In this paper, the photochromic behavior of yttrium hydride thin films was investigated and it was concluded that the photo-chromic effect can be explained by the gradual growth, under illumination, of metallic domains within the initial wideband-gap semiconducting lattice.
Abstract: Oxygen-containing yttrium hydride thin films exhibit photochromic behavior: Transparent thin films reversibly switch from a transparent state to a photodarkened state after being illuminated with UV or blue light. From optical spectrophotometry and ellipsometry measurements of the transparent state and photodarkened state, it is concluded that the photochromic effect can be explained by the gradual growth, under illumination, of metallic domains within the initial wide-band-gap semiconducting lattice. This conclusion is supported by Raman measurements.
TL;DR: In this paper, high aspect ratio titanium nitride (TiN) grating structures are fabricated by the combination of deep reactive ion etching (DRIE) and atomic layer deposition (ALD) techniques.
Abstract: High aspect ratio titanium nitride (TiN) grating structures are fabricated by the combination of deep reactive ion etching (DRIE) and atomic layer deposition (ALD) techniques. TiN is deposited at 500 °C on a silicon trench template. Silicon between vertical TiN layers is selectively etched to fabricate the high aspect ratio TiN trenches with the pitch of 400 nm and height of around 2.7 μm. Dielectric functions of TiN films with different thicknesses of 18 – 105 nm and post-annealing temperatures of 700 – 900 °C are characterized by an ellipsometer. We found that the highest annealing temperature of 900 °C gives the most pronounced plasmonic behavior with the highest plasma frequency, ωp = 2.53 eV (λp = 490 nm). Such high aspect ratio trench structures function as a plasmonic grating sensor that supports the Rayleigh-Woods anomalies (RWAs), enabling the measurement of changes in the refractive index of the ambient medium in the wavelength range of 600 – 900 nm. We achieved the bulk refractive index sensitivity (BRIS) of approximately 430 nm/RIU relevant to biosensing liquids.
TL;DR: In this article, the effect of annealing temperature on the structural and optical properties of ZnO thin films was investigated by X-ray diffractometer (XRD), atomic force microscope (AFM), UV-VIS spectrophotometry and ellipsometry.
TL;DR: An electrochemical response and a voltage-induced insulator-to-metal transition in the vertical metal-vanadium oxide-metal device structure were observed for V2O5 and VO2 films, respectively.
Abstract: Atomic layer deposition was adopted to deposit VOx thin films using vanadyl tri-isopropoxide {VO[O(C3H7)]3, VTIP} and water (H2O) at 135 °C The self-limiting and purge-time-dependent growth behaviors were studied by ex situ ellipsometry to determine the saturated growth conditions for atomic-layer-deposited VOx The as-deposited films were found to be amorphous The structural, chemical, and optical properties of the crystalline thin films with controlled phase formation were investigated after postdeposition annealing at various atmospheres and temperatures Reducing and oxidizing atmospheres enabled the formation of pure VO2 and V2O5 phases, respectively The possible band structures of the crystalline VO2 and V2O5 thin films were established Furthermore, an electrochemical response and a voltage-induced insulator-to-metal transition in the vertical metal–vanadium oxide–metal device structure were observed for V2O5 and VO2 films, respectively
TL;DR: The tunable properties of the plasmon resonance wavelength in Ga NPs are supported by thermal oxidation at low temperatures without significant reduction of thePlasmon Resonance intensity.
Abstract: The effect of the oxidation of gallium nanoparticles (Ga NPs) on their plasmonic properties is investigated. Discrete dipole approximation has been used to study the wavelength of the out-of-plane localized surface plasmon resonance in hemispherical Ga NPs, deposited on silicon substrates, with oxide shell (Ga2O3) of different thickness. Thermal oxidation treatments, varying temperature and time, were carried out in order to increase experimentally the Ga2O3 shell thickness in the NPs. The optical, structural and chemical properties of the oxidized NPs have been studied by spectroscopic ellipsometry, scanning electron microscopy, grazing incidence x-ray diffraction and x-ray photoelectron spectroscopy. A clear redshift of the peak wavelength is observed, barely affecting the intensity of the plasmon resonance. A controllable increase of the Ga2O3 thickness as a consequence of the thermal annealing is achieved. In addition, simulations together with ellipsometry results have been used to determine the oxidation rate, whose kinetics is governed by a logarithmic dependence. These results support the tunable properties of the plasmon resonance wavelength in Ga NPs by thermal oxidation at low temperatures without significant reduction of the plasmon resonance intensity.
TL;DR: In this article, the complex refractive index of methylammonium lead iodide (CH3NH3PbI3) perovskite thin films obtained by means of variable angle spectroscopic ellipsometry and transmittance/reflectance spectrophotometry in the wavelength range of 190nm to 2500nm was reported.
Abstract: We report the complex refractive index of methylammonium lead iodide (CH3NH3PbI3) perovskite thin films obtained by means of variable angle spectroscopic ellipsometry and transmittance/reflectance spectrophotometry in the wavelength range of 190 nm to 2500 nm. The film thickness and roughness layer thickness are determined by minimizing a global unbiased estimator in the region where the spectrophotometry and ellipsometry spectra overlap. We then determine the optical bandgap and Urbach energy from the absorption coefficient, by means of a fundamental absorption model based on band fluctuations in direct semiconductors. This model merges both the Urbach tail and the absorption edge regions in a single equation. In this way, we increase the fitting region and extend the conventional ( α ℏ ω ) 2-plot method to obtain accurate bandgap values.
TL;DR: In this article, a detailed study of the post-deposition thermal processing and material properties of Sb 2 S 3 thin films deposited by thermal evaporation under vacuum was performed.
TL;DR: In this paper, ZnO-NiO nanocomposites thin films were elaborated at different mixing concentrations using sol gel and spin coating methods using XRD diffraction and Raman spectra.
Abstract: Spectroscopic ellipsometry is a means to investigate optical and dielectric material responses. Conventional spectroscopic ellipsometry has trade-offs between spectral accuracy, resolution, and measurement time. Polarization modulation has afforded poor performance due to its sensitivity to mechanical vibrational noise, thermal instability, and polarization wavelength dependency. We equip a spectroscopic ellipsometer with dual-optical-comb spectroscopy, viz. dual-optical-comb spectroscopic ellipsometry (DCSE). The DCSE directly and simultaneously obtains amplitude and phase information with ultra-high spectral precision that is beyond the conventional limit. This precision is due to the automatic time-sweeping acquisition of the interferogram using Fourier transform spectroscopy and optical combs with well-defined frequency. Ellipsometric evaluation without polarization modulation also enhances the stability and robustness of the system. In this study, we evaluate the DCSE of birefringent materials and thin films, which showed improved spectral accuracy and a resolution of up to 1.2x10-5 nm across a 5-10 THz spectral bandwidth without any mechanical movement.
TL;DR: In this article, the dispersion of optical constants in a wide temperature range and the transmittance predicted using the optical constants were investigated for thermochromic VO 2 prepared by reactive high-power impulse magnetron sputtering and characterized by spectroscopic ellipsometry.
TL;DR: In this paper, the authors implemented electronic structure calculations as well as ellipsometry experiments to study the finite temperature dielectric functions of noble metals Au, Ag, and Cu.
Abstract: Realistic representation of finite temperature dielectric functions of noble metals is crucial in describing the optical properties of advancing applications in plasmonics and optical metamaterials. However, the atomistic origins of the temperature dependence of noble metals' dielectric functions still lack full explanation. In this paper, we implement electronic structure calculations as well as ellipsometry experiments to study the finite temperature dielectric functions of noble metals Au, Ag, and Cu. Theoretically, the intraband dielectric function is described by the Drude model, of which the important quantity electron lifetime is obtained by considering the electron-phonon, electron-electron, and electron-surface scattering mechanism. The electron-phonon coupling is key to determining the temperature dependence of electron lifetime and intraband dielectric function. For the interband dielectric function, it arises from the electronic interband transition. Due to the limitation of incorporating electron-phonon coupling into the interband transition scheme, the temperature dependence of the interband dielectric function is mainly determined by the thermal expansion effect. Experimentally, variable angle spectroscopic ellipsometry measures the dielectric functions of Au and Ag over the temperature range of 300--700 K and spectral range of 2--20 \textmu{}m. Those experimental measurements are consistent with theoretical results and thus verify the theoretical models for the finite temperature dielectric function.
TL;DR: In this paper, the authors demonstrate that there is a significant drop in the magnitudes of both the real and imaginary parts of complex dielectric constants and in near-band gap absorption along with a blue shift of the absorption edge with decreasing film thickness at and below ∼20nm.
TL;DR: In this article, a transferrable single crystalline 4H-SiC nanomembrane (SiC NM) is demonstrated, which is released from a SiC-on-insulator (SiCOI) wafer.
Abstract: In this work, we demonstrate a transferrable single crystalline 4H-SiC nanomembrane (SiC NM) released from a SiC-on-insulator (SiCOI) wafer. High resolution X-ray diffraction (XRD) and atomic force microscopy (AFM) were performed on the SiC NM and confirmed similarly good crystallinity and surface morphology. In addition, the refractive index and extinction coefficient of the SiC NM were investigated using ellipsometry analyses. Despite its thinness (i.e., 200 nm), the SiC NM achieved an absorption greater than 40% in the wavelength range of 200–260 nm with a maximum absorption of 73.8% at 256 nm. Our transferrable SiC NM provides not only good mechanical flexibility, but also exhibits excellent ultraviolet (UV) light absorption which could be readily utilized for high sensitivity flexible UV detectors.
TL;DR: In this paper, a double-layer model with sharp interfaces was established for fitting of the ellipsometry parameters of amorphous and polycrystalline WO3 films.
TL;DR: In this paper, the authors present influence of manufacturing parameters on optical properties and surface morphology of composite materials with a polymer matrix reinforced by TiO 2 and SiO 2, and Bi 2 O 3 nanoparticles.
TL;DR: In this article, a memristive response was acquired from a number of these cells, revealing a dependence of the electrical behavior on minor changes in the TiO2 structure, electroforming parameters, and architecture.
Abstract: We report the development of sol–gel derived TiO2 thin films with adjustable and defined properties suitable for memristive cell fabrication. Memristive cells were developed by the sol–gel deposition of titania onto SiO2/Ti/Pt engineered electrodes via spin coating, followed by diverse curing and annealing procedures. The influence of the processing conditions and the sol's chemical composition on the film properties, and therefore on the memristive response, was studied by micro-Raman and transmission spectroscopies, profilometry, ellipsometry, X-ray photoelectron spectroscopy (XPS), atomic force microscopy (AFM), and X-ray absorption and diffraction spectroscopies (XAS and XRD). A memristive response was acquired from a number of these cells, revealing a dependence of the electrical behavior on minor changes in the TiO2 structure, electroforming parameters, and architecture. Thus, these properties provide a handle for fine-tuning electrical performance.