Optical Properties Of Layers Research Articles

Quantitative estimation of optical properties in bilayer media within the subdiffusive regime using tilted fiber-optic probe diffuse reflectance spectroscopy, part 2: probe design, realization, and experimental validation.

Tissues like skin have a layered structure where each layer's optical properties vary significantly. However, traditional diffuse reflectance spectroscopy assumes a homogeneous medium, often leading to estimations that reflects the properties of neither layer. There's a clear need for probes that can precisely measure the optical properties of layered tissues. This paper aims to design a diffuse reflectance probe capable of accurately estimating the optical properties of bilayer tissues in the subdiffusive regime. Using Monte Carlo simulations, we evaluated key geometric factors-fiber placement, tilt angle, diameter, and numerical aperture-on optical property estimation, following the methodology in Part I. A robust design is proposed that balances accurate intrinsic optical property (IOP) calculations with practical experimental constraints. The designed probe, featuring eight illumination and eight detection fibers with varying spacings and tilt angles. The estimation error of the IOP calculation for bilayer phantoms is less than 20% for top layers with thicknesses between 0.2 and 1.0mm. Building on the approach from Part I and using a precise calibration, the probe effectively quantified and distinguished the IOPs of bilayer samples, particularly those relevant to early skin pathology detection and characterization.

Atomic layer deposition, mechanical, wear resistance, and optical properties of (Cr1-xAlx)2O3 films on Si (100)

This study presents the comparison of microstructure, mechanical, tribological, and optical properties of the ternary chromium-aluminum oxide films ((Cr1-xAlx)2O3) with binary Cr2O3 and Al2O3 films, deposited by atomic layer deposition at 275 °C. The atomic growth per cycle of the Al atoms increased from 3.1 to 8.5 atoms/nm2 on chromium oxide film. The Al2O3 films were X-ray amorphous. The Cr2O3 films contained crystallites of the eskolaite phase. Nano-size (diameter from 3 to 5 nm) crystallites with cubic symmetry and matching with that of cubic γ-Al2O3 or η-Al2O3 phases were observed in (Cr1-xAlx)2O3 films. The ternary film with Al/(Al + Cr) of 0.40 showed the highest hardness (18.4 GPa) and elastic modulus (169.4 GPa), whereas the wear rate of this film decreased by ∼80 % compared with Cr2O3 films. Optical band gap energy values corresponding to the indirect transition model decreased from 2.93 eV for the Cr2O3 film to 2.58 eV for the Cr-Al-O films.

The Biopolymer Active Surface for Optical Fibre Sensors.

Optical fibre sensors have the potential to be overly sensitive and responsive, making them useful in various applications to detect the presence of pollutants in the environment, toxic gasses, or pesticides in soil. Deoxyribonucleic acid (DNA) as biopolymer active surfaces for fibre sensors can be designed to detect specific molecules or compounds accurately. In the article, we propose to use an optical fibre taper and DNA complex with surfactant-based sensors to offer a promising approach for gas detection, including ammonia solution, 1,4 thioxane, and trimethyl phosphate imitating hazardous agents. The presented results describe the influence of the adsorption of evaporation of measured agents to the DNA complex layer on a light leakage outside the structure of an optical fibre taper. The DNA layer with additional gas molecules becomes a new cladding of the taper structure, with the possibility to change its properties. The process of adsorption causes a change in the layer's optical properties surrounding a taper-like refractive index and increasing layer diameter, which changes the boundary condition of the structure and interacts with light in a wide spectral range of 600-1200 nm. The research's novelty is implementing a DNA complex active surface as the biodegradable biopolymer alignment for optical devices like in-line fibre sensors and those enabled for hazardous agent detection for substances appearing in the environment as industrial or even warfare toxic agents.

Deep-learning-based inverse design of colloidal quantum dots

Because optical properties of colloidal quantum dots (QDs) greatly depend on their layer thicknesses at the sub-nanometer scale, accurately predicting optical properties based on these structural parameters can help streamline the development process. However, most of traditional inverse design approaches require time-consuming numerical simulations and optimization processes. In this simulation-only paper, we propose a deep-learning-based inverse design model for colloidal InP/ZnSe/ZnS QDs based on the structure parameters of layer thicknesses and optical properties of the emission and absorption spectrum. Four different deep neural network (DNN) structures are implemented and compared. A tandem DNN structure with the simultaneous use of both emission and absorption spectra as input data shows the best accuracy due to its ability to alleviate the non-uniqueness problem in the inverse design of colloidal QDs. Our inverse design model enables the prediction of layer thicknesses for QDs that exhibit on-demand optical emission/absorption spectra, which are particularly enhanced at the specific target wavelength region. Moreover, the weights and biases of the well-trained tandem DNN for InP/ZnSe/ZnS QDs can be transferred and tuned to implement a transfer-learning-assisted inverse design model for CdSe/ZnSe/ZnS QDs, where the amount of training data to achieve the average prediction accuracy of 99.3 % is reduced by a maximum of 71.4 %.

Optical loss analysis of Sb2S3 and Sb2Se3 thin film solar cells: A Quantitative Assessment

Optical loss either by light reflection, or light absorption in different layers of a solar cell, can significantly impact short-circuit current density. In this paper, an optical model has been developed to analyze the optical loss in thin film solar cells made of CdS/Sb2S3 or CdS/Sb2Se3 antimony chalcogenide. This model is based on optical loss from absorption in thin layers and reflection at the interfaces of glass/TCO/CdS/(Sb2S3 or Sb2Se3) only by considering the optical properties of layers (refractive index and extinction coefficient). The transmission and reflection rate of Sb2S3 or Sb2Se3 show almost a similar trend. The absorptivity and relative loss in short-circuit current density (Jsc) versus the thickness of Sb2S3 and Sb2Se3 layers was calculated for two different structures: glass/TCO/CdS/Sb2S3 and glass/TCO/CdS/Sb2Se3. The Sb2Se3 solar cell shows a slightly better conversion performance compared to Sb2S3 solar cell due to lower reflection loss. The light reflection was calculated at four interfaces. The transmission rate of light through TCO, ITO, and CdS layers was calculated to obtain an optimal thickness for these layers. TCO showed a higher transmission rate and thus is preferred in antimony solar cell structures. The variations of (Jsc) and loss for Jsc with different thicknesses of ITO (>20%) or TCO (<20%) contact layers, favoring TCO for its lower optical losses and higher Jsc (24 mA cm−2).

Ti doped Cr2O3 thin films: Atomic layer deposition, mechanical and optical properties

Atomic layer deposition (ALD) of titanium doped chromium oxide (CTO) films on Si (100) and SiO2 substrates was studied using deposition formula of n× (CrO2Cl2 - CH3OH) + m × (TiCl4 - H2O). The CTO films contained α-Cr2O3 eskolaite phase when deposited at Ti/(Ti+Cr) atomic ratio values of 0–0.24. During the first ALD super cycle, the growth rate of the Ti-O on chromium oxide was 2.4 times higher compared to that on TiO2 and was explained by the differences of densities of oxygen atoms on the (001) plane of eskolaite compared to their density on (001) plane of anatase. At the same time only minor influence on the growth rate of chromium oxide depending on the Ti amount was detected. The hardness value of 20.5 GPa was obtained for CTO films at Ti/(Ti+Cr) atomic ratio of 0.24, higher than 14.8 and 12.2 GPa obtained for pure chromium and titanium oxide thin films, respectively. The doping of the chromium oxide with titanium increased the absorbance of the films in the wavelength range of 350 – 450 nm and decreased the band gap energy corresponding to the indirect transition from 3.0 eV for pure Cr2O3 to 2.2 eV.

Deposition of Cu2ZnSnS4 layers by a novel single flash thermal evaporator from mixture element powder

This research studies the deposition ability of Cu2ZnSnS4 from a mixed element powder and without sulfurization by a novel flash single thermal evaporator technique. Elemental powders of the source, S, Sn, Zn, and Cu, are held in an evaporation boat to mix their vapour together and to evaporate the mixture at a high temperature. The effect of substrate temperature on the thin layers structure properties, optical properties and surface morphology is explored by X-ray diffraction, Raman spectroscopy, scanning electron microscopy, energy dispersive X-ray, atomic force microscopy, and UV-Vis -NIR spectroscopy. Cu2ZnSnS4 films of kesterite structures are fabricated successfully at various substrate temperatures by this technique in one step without a sulfurization process. The substrate temperatures affect the composition and optical properties of the prepared layers by changing the concentration of elements and crystallinity. The layer prepared at 250°C exhibits an optimal stoichiometry and an optical bandgap value of 1.51 eV.

Synthesis of a large area ReS2 thin film by CVD for in-depth investigation of resistive switching: effects of metal electrodes, channel width and noise behaviour.

The anisotropic crystal structure and layer independent electrical and optical properties of ReS2 make it unique among other two-dimensional materials (2DMs), emphasizing a special need for its synthesis. This work discusses the synthesis and in-depth characterization of a 1 × 1 cm2 large and few layered ReS2 film. Vibrational modes and excitonic peaks observed from the Raman and photoluminescence (PL) spectra corroborated the formation of a ReS2 film with a 1.26 eV bandgap. High resolution transmission electron microscopy (HRTEM) images and selected area electron diffraction (SAED) patterns inferred the polycrystalline nature of the film, while cross-sectional field emission scanning electron microscopy (FESEM) indicated planar growth with ∼10 nm thickness. The chemical composition of the film analysed through X-ray photoelectron spectroscopy (XPS) indicated the formation of a ReS2 film with a Re : S atomic ratio of 1 : 1.75, indicating a small amount of non-stoichiometric RexSy. Following the basic characterization studies, the ReS2 film was tested for resistive switching (RS) device application in which the effects of different metal electrodes (Pt/Au and Ag/Au) and different channel widths (200, 100, and 50 μm) were studied. The highest memory window equal to 108 was obtained for the Ag/Au electrode while Pt/Au showed a memory window of 102. RS for the former was ascribed to the formation of a conducting filament (CF) because of the migration of Ag+ ions, while defect mediated charge carrier transport led to switching in the Pt/Au electrode. Furthermore, the RHRS/RLRS ratio achieved in this work (108) is also of the highest magnitude reported thus far. Furthermore, a comparison of devices with Ag/Au electrodes but with different channel widths (50, 100 and 200 μm) gave insightful results on the existence of multiple resistance states, device endurance and retention. An inverse relationship between the retention time and the device's channel width was observed, where the device with a 50 μm channel width showed a retention time of 48 hours, and the one with a 200 μm width showed stability only up to 3000 s. Furthermore, low frequency noise measurements were performed to understand the effect of defects in the low resistance state (LRS) and the high resistance state (HRS). The HRS exhibited Lorentzian noise behaviour while the LRS exhibited Lorentzian only at low current bias which converged to 1/f noise at higher current bias.

Construction of Bi2O3 quantum Dots/SrBi4Ti4O15 S-scheme heterojunction with enhanced photocatalytic CO2 reduction: Role of Bi2O3 quantum dots and mechanism study

The development of layered structure (Bi2O2)2+ semiconductors have received extensive concern in energy and environment research attributable to their distinct layered structure, optical and electronic properties. However, the low charge separation efficiency and the tardy electron transfer process are limited the large-scale studies of bismuth-based materials. Herein, Bi2O3 quantum dots/SrBi4Ti4O15 S-scheme heterojunction (SBTO-1) with atomically ultra-thin structure is successfully synthesized through hydrothermal method by using hexadecyl trimethyl ammonium bromide (CTAB) as assistant. As compared with solely SrBi4Ti4O15, electrochemical tests showed that the as-prepared heterojunction greatly shortened the electron diffusion distance inside the photocatalyst and significantly increased the separation of electron-hole pairs. Meanwhile, the SBTO-1 heterojunction constructed based on Bi2O3 quantum dots can enhance the specific surface area and increase the active sites. Consequently, this S-scheme heterojunction material showed superior photocatalytic performance that CO and CH4 generations reach up to 73.0 and 30.2 μmolg−1, respectively, which are about 3 and 30 times higher than the pure SrBi4Ti4O15. More importantly, even under the air atmosphere, the SBTO-1 composite still presented excellent photocatalytic CO2 reduction ability. Density functional theory (DFT) calculations and electron paramagnetic resonance (EPR) confirmed that electrons can be transferred to SrBi4Ti4O15 by Bi2O3 after constructing heterojunction, which has excellent charge separation ability. In-situ infrared further explained that the bidentate formate species (COO- and -HCOO-) were a crucial intermediate for photocatalytic CO2 reduction. This study provided some fresh insights for the design of bismuth-based photocatalysts that can capture CO2 significantly and effectively transform CO2.

The effect of deposition angle and thickness on structural and optical properties of manganese oxide thin films

Manganese oxide thin films were deposited on glass substrates by electron gun evaporation method under ultra-high vacuum condition. Thickness of the layers was measured 60 and 120 nm, by a quartz crystal method. Deposition conditions such as deposition rate, vacuum pressure, incidence of angle and substrate temperature were the same for all layers. After producing pure manganese oxide layers a post-annealing method was used in the presence of a uniform oxygen flow of 300 (sccm) and at 600 K annealing temperature. Optical reflectance and transmittance of the layers were measured in the wavelength of 350–850 nm by a spectrophotometer. Kramers–Kronig relations were used to calculate the optical constant. The influence of annealing temperature and oxygen flow on optical properties is investigated. It was found that film thickness and deposition angle plays an important role on the nanostructures as well as optical properties of layers and cause significant variations in behavior of thin manganese oxide films. The physical properties of materials were characterized by X-ray diffraction (XRD), FE-SEM, AFM, EDX, and UV–Vis techniques.

Polarized discrete ordinate adding approximation for infrared and microwave radiative transfer

A POLarized Discrete ordinate aDding Approximation (POLDDA) is proposed to solve the vector thermal radiative transfer equation in a vertically inhomogeneous plane-parallel atmosphere. The discrete ordinates method is employed to find the single-layer solution for vector thermal radiative transfer; this is an extension of the approach for scalar radiative transfer, with the I- and Q-components being dealt with in a parallel way by using a doubled dimension in the discrete ordinate space. Chandrasekhar’s invariance principle is used to drive the adding process for the connection of multiple layers. This adding process has no restriction on the layer optical properties. The accuracy and efficiency of POLDDA are evaluated under different atmospheric conditions for different number of computational quadrature angles (streams). It is shown that the relative differences between POLDDA (using 32 or 16 streams) and the benchmark calculations (PolRadtran/RT3 with 32 streams, a typical model based on the adding-doubling method) are negligible for both I- and Q-components. When 8 streams are used, the accuracy of POLDDA slightly decreases, but still higher than that of 8-stream RT3. The computational efficiency of POLDDA is much higher than RT3, especially for large optical depths and when a large number of streams (≥ 16) are used. Unlike RT3, the computational time of POLDDA is always the same regardless of the optical depth.

Scanning-resonance optical sensing based on a laterally graded plasmonic layer—optical properties of Ag[formula omitted]Al[formula omitted] in the range of [formula omitted] to 1

Plasmonic AgAl/Si3N4 sensor layer structure was deposited on a fused silica glass slide by dual DC magnetron sputtering. The composition of the AgxAl1−x layer was laterally graded in which x linearly changes from x=0 to x=1 over a distance of 20 mm. The Si3N4 layer serves both as a resonator and a protective layer providing homogeneous chemical properties on top of the inhomogeneous AgAl layer. The structure was illuminated through a hemi-cylinder for variable-angle measurements in the Kretschmann–Raether configuration using a focused spot that enabled the change of x by moving it along the gradient of the composition. Optical properties of AgxAl1−x in the whole composition range were obtained. The positions of resonant peaks were shifted by changing the angle of incidence and the lateral position of the spot in a flow-cell configuration. The optical sensing performance of the bilayer system was investigated for x=0 and x=1. Based on the capabilities of ellipsometry limit of detection in refractive index unit values of ≈4−8⋅10−6 can be achieved in the resonant positions utilizing both p- and s-polarizations. Due to the flexible tunability of the resonant wavelengths by moving a focused spot, the above sensitivity is available in-situ, over the spectral range of 265-1504 nm.

Two-dimensional bilayer MoS2 flakes with variable size of the upper layer grown by chemical vapor deposition

Bilayer transition-metal dichalcogenides, particularly twisted bilayer, provide a promising platform for the exploration of novel fundamental properties and applications in valleytronics and twistronics. Here, we report the growth of two-dimensional (2D) bilayer molybdenum disulfide (MoS2) flakes with varied upper-layer size by a conventional space-confined chemical vapor deposition. The area ratio of upper layer/bottom layer of these bilayer flakes at the difference locations along the gas-flow direction is estimated to be 5% (S1), 35% (S2), 73% (S3), and 100% (S4), respectively. The detailed layer number and optical properties of these samples have been evaluated by AFM, Raman, and PL characterizations. Furthermore, the evolution of area ratio of upper layer/bottom layer is unveiled by the energy and precursors concentration variation along the gas flow direction during the narrow space. Our results provide a feasible approach for the fabrication of 2D bilayer TMDCs crystals that can accelerate the performance study and promising applications.

Influence of source-detector separation on diffuse correlation spectroscopy measurements of cerebral blood flow with a multilayered analytical model.

.Significance: Diffuse correlation spectroscopy (DCS) is an emerging noninvasive optical technology for bedside monitoring of cerebral blood flow. However, extracerebral hemodynamics can significantly influence DCS estimations of cerebral perfusion. Advanced analytical models can be used to remove the contribution of extracerebral hemodynamics; however, these models are highly sensitive to measurement noise. There is a need for an empirical determination of the optimal source–detector separation(s) (SDS) that improves the accuracy and reduces sensitivity to noise in the estimation of cerebral blood flow with these models.Aim: To determine the influence of SDS on solution uniqueness, measurement accuracy, and sensitivity to inaccuracies in model parameters when using the three-layer model to estimate cerebral blood flow with DCS.Approach: We performed a series of in silico simulations on samples spanning a wide range of physiologically-relevant layer optical properties, thicknesses, and flow. Data were simulated at SDS ranging from 0.5 to 3.0 cm using the three-layer solution to the correlation diffusion equation (with and without noise added) and using three-layer slab Monte Carlo simulations. We quantified the influence of SDS on uniqueness, accuracy, and sensitivity to inaccuracies in model parameters using the three-layer inverse model.Results: Two SDS are required to ensure a unique solution of cerebral blood flow index (CBFi). Combinations of 0.5/1.0/1.5 and 2.5 cm provide the optimal choice for balancing the depth penetration with signal-to-noise ratio to minimize the error in CBFi across a wide range of samples with varying optical properties, thicknesses, and dynamics.Conclusions: These results suggest that the choice of SDS is critical for minimizing the estimated error of cerebral blood flow when using the three-layer model to analyze DCS data.

Color-matching techniques for creating esthetic hand and finger prostheses.

Color matching is a critically important part of, and by far, also the most challenging aspect of producing esthetic silicone prosthesis. There is a knowledge gap in the literature and a lack of opportunities for training in the expertise, particularly regarding color-matching techniques. This article details a color-matching technique that is able to achieve life-like coloration in esthetic prosthesis. Each prosthesis is molded in an outer and inner layers of silicone tinted to different shades and opacities incorporating an intermediate touch-up layer to reproduce the detailed coloration of the hand (because of the presence of veins, finger joint/dermal pigmentations, a vascularized nail bed, and pinkish palm). This method of color-matching prosthesis combining intrinsic and extrinsic techniques simulates the layered anatomy and optical properties of the human skin to effectively replicate its esthetic and life-like coloration. Technical tips for achieving an accurate color match to the patient's skin, including pigment formulation adjustments for a tanned vs. a fair skin, and for painting the touch-up details are discussed. Methods for modifying the color tones of completed prosthesis and for minimizing metameric color differences when the prosthesis is viewed under different light sources are also presented. The technique is instrumental in achieving good outcomes for life-likeness and esthetic coloration in the prostheses fitted at our center. Studies previously published that investigated patients' evaluation of important esthetic characteristics of their prosthesis after a period of adjustment to fitting have shown a generally high level of patient satisfaction.

Modeling parasitic absorption in silicon solar cells with a near-surface absorption parameter

One drawback of passivating contacts in crystalline silicon solar cells is the current loss due to parasitic absorption within the involved material layers. When employed on an illuminated side of the cell, the full spectrum of the incident light will be partly absorbed before reaching the silicon bulk. Additionally, near-infrared (NIR) absorption can substantially reduce the cell's NIR spectral response (SR) also when employed on the non-illuminated side. As those losses are hard to measure directly, optical modeling is crucial for their quantification. This paper presents an extension to an analytical light-trapping model to account for parasitic absorption in the near-surface region via a new parameter A ppp (absorbed fraction per perpendicular pass). We test the model by analyzing i) reflectance measurements on samples with varying doping profiles, ii) SR measurements on TOPCon solar cells with varying back-side poly-silicon layers, and iii) SR measurements of a bifacial silicon heterojunction cell. We show that the model can well be calibrated by fitting a single value for A ppp to reflectance measurements. This enables a quantification of the parasitic absorption loss without requiring knowledge of all layer's optical properties. The model also is able to predict parasitic absorption in TOPCon cells when knowing the thickness and doping density of the poly-Si layer. Having proven the usefulness of A ppp to represent parasitic absorption as a single-valued quantity, we suggest A ppp as a third figure of merit for the quality of a passivating contact, next to the recombination parameter J 0c and the contact resistivity ρ c . • New parameter A ppp quantifies near-surface parasitic absorption in a c-Si solar cell. • A ppp extends an existing analytical light-trapping model. • Model can be fitted to reflectance to quantify parasitic absorption current loss. • Proposed as third figure of merit for a passivating contact besides J 0c and ρ c .

Accuracy of diffuse correlation spectroscopy measurements of cerebral blood flow when using a three-layer analytical model.

Diffuse correlation spectroscopy (DCS) is a non-invasive optical technology for the assessment of an index of cerebral blood flow (CBFi). Analytical methods that model the head as a three-layered medium (i.e., scalp, skull, brain) are becoming more commonly used to minimize the contribution of extracerebral layers to the measured DCS signal in adult cerebral blood flow studies. However, these models rely on a priori knowledge of layer optical properties and thicknesses. Errors in these values can lead to errors in the estimation of CBFi, although the magnitude of this influence has not been rigorously characterized. Herein, we investigate the accuracy of measuring cerebral blood flow with a three-layer model when errors in layer optical properties or thicknesses are present. Through a series of in silico experiments, we demonstrate that CBFi is highly sensitive to errors in brain optical properties and skull and scalp thicknesses. Relative changes in CBFi are less sensitive to optical properties but are influenced by errors in layer thickness. Thus, when using the three-layer model, accurate estimation of scalp and skull thickness are required for reliable results.

Analysis of a tunable CMOS-compatible multilayer waveguide structure for dual polarizer-modulator operation

A multilayer structure using graphene on a silicon waveguide is introduced and optimized to operate as a tunable TE-pass polarizer at 1310 nm or 1550 nm, a tunable TE/TM modulator at 1310 nm or 1550 nm, and a dual operation as a modulator at 1310 nm and a polarizer at 1550 nm. Analysis and optimization are based on the waveguide structure modal loss, geometry, and the 2D graphene layer optical properties dependency on the applied chemical potential. The polarizer tunability at 1310 nm or 1550 nm is attainable setting the applied chemical potential range from 0.55–0.65 eV or 0.45–0.55 eV, respectively. For the modulator tunability at 1310 nm or 1550 nm, the applied chemical potential ranges from 0.45–0.55 eV or 0.35–0.45 eV, respectively. The optimized waveguide silicon layer around 210 nm guarantees an extinction ratio better than 0.056 dB/µm for the polarizer and better than 0.045/0.133 dB/µm for the TE/TM modulator at 1310 nm, and better than 0.034 dB/µm for polarizer and better than 0.053/0.137 dB/µm for TE/TM modulator at 1550 nm. The dual polarizer-modulator operation, e.g., a modulator operating at 1310 nm and a polarizer operating at 1550 nm, is attained at the 0.45–0.55 chemical potential range with an extinction ratio better than 0.045 dB/µm and 0.034 dB/µm, respectively. Compared with other similar devices, the advantage of the structure relies on its versatility to operate as both modulator and polarizer, at different wavelengths, via a proper choice of applied chemical potential, with an insertion loss lower than 0.007 dB/µm.

Influence of thickness and deposition angle on structural and optical properties of manganese oxide thin films

Manganese oxide thin films were produced on glass substrates by resistive evaporation at room temperature. The layers with different thickness (30 and 90 nm) at different deposition angles (0 and 40°) were prepared by electron gun evaporation method under ultra-high vacuum condition. After deposition of pure manganese oxide thin films a post-annealing process was used in a uniform oxygen flow of 300 (sccm) and at 500 K annealing temperature. Optical transmittance and reflectance of the layers were measured in the wavelength of 350–850 nm by a spectrophotometer. Kramers–Kronig relations were used to calculate the optical constants. The influence of oxygen flow and annealing temperature on optical properties is investigated. It was found that film thickness and deposition angle plays a significant role on the nanostructures as well as optical properties of layers and cause major variations in behavior of thin manganese oxide films. The physical properties of materials were characterized by X-ray diffraction (XRD), FE-SEM, AFM, EDAX, and UV-VIS techniques.

Optical and Microstructural Characterization of Thin Layers

The microstructure and optical properties of layers strongly depend on the method of synthesis. This Special Issue on “Optical and Microstructural Characterization of Thin Layers” is a collection of papers on the relationships between the growth conditions and specific properties of thin films.