Optical Properties Of Films Research Articles

Structural and optical properties of cubic GaN films on high-thermal conductivity substrates

A thin cubic-GaN epitaxial layer was grown by plasma-assisted molecular-beam epitaxy directly on a (100) cubic-boron-nitride nucleation layer that was previously deposited on a (100)-oriented, type IIA, single-crystal chemical-vapor deposition diamond substrate. X-ray diffraction measurements verified that (100)-plane zincblende is the dominant crystal structure of the GaN layer, with a small contribution from the wurtzite phase in some sample regions. Detailed atomic force microscopy and Raman scattering measurements confirmed the XRD findings. Low temperature photoluminescence spectra show a dominant emission line near 3.12 eV and a weaker emission line near 3.21 eV. The former is assigned to a recombination process involving electrons bound to shallow donors with holes bound to shallow acceptors (donor–acceptor pair recombination process). The latter, which becomes dominant at temperatures above 50 K, is assigned to a recombination process involving the annihilation of excitons bound to shallow impurities. Room temperature transmission measurements yielded a direct bandgap of 3.23 eV, which is close to the reported values for c-GaN. These results confirm that cubic-GaN was successfully deposited on a high thermal-conductivity diamond substrate. This opens the door to exploring the potential of cubic-GaN devices for high-power applications, given that large area diamond substrates are becoming available.

Chiral nematic cellulose nanocrystal films: Sucrose modulation for structural color and dynamic behavior.

This study explores the effect of sucrose addition on the properties of chiral nematic cellulose nanocrystal (CNC) films for potential food industry applications, including biodegradable packaging and food coloring. The addition of sucrose altered the films' structural color, shifting from blue in pure CNC films to aqua blue, green, yellow-green, and red with increasing sucrose concentrations (up to 21%). Surface analysis revealed a reduction in contact angle from 96° to 48° due to sucrose's hydrophilic nature and smoother film surfaces. XRD results indicated a decrease in crystallinity from 84.5% to 15.6%, linked to the disruption of CNC alignment by sucrose. Mechanical testing showed reduced tensile strength (138MPa to 35MPa) and Young's modulus (1.634GPa to 70MPa) with higher sucrose content. Notably, over the storage time, films with 21% sucrose exhibited dynamic structural coloration caused by localized sucrose recrystallization, leading to pitch shifts and color transitions. These findings demonstrate the tunable optical and mechanical properties of CNC-sucrose films, positioning them as promising materials for sustainable food packaging and responsive coatings.

Impact of Ag Doping on the Structural, Optical, and Photovoltaic Properties of MAPbI2Br Thin Films

Impact of Ag Doping on the Structural, Optical, and Photovoltaic Properties of MAPbI2Br Thin Films

Effect of N2 gas fractions on improvement of structural, optical, and electrical properties of Cu3N thin films deposited by reactive radio frequency magnetron sputtering

Effect of N2 gas fractions on improvement of structural, optical, and electrical properties of Cu3N thin films deposited by reactive radio frequency magnetron sputtering

Characterization of octenyl succinylated potato-starch based films enriched with extracts from various honey-bee products

The study developed octenyl succinylated (OS) potato starch complexes with ethanolic extracts of honey bee products (HBE) and assess their effects on starch-based films properties. X-ray diffraction and thermogravimetric analysis showed that OS starch films had lower crystallinity and higher thermal stability than native ones. Adding HBE enhanced V-type ordering in OS films. Starch esterification raised the water contact angle (WCA) from 52.9° to 62.3°, with hydrophobicity improvements when HBE was added (WCA >78.9°). OS starch-HBE complexes increased the antioxidant properties compared to non-modified starch films, in the order: propolis > bee bread > bee pollen > buckwheat honey > multiflower honey. The sum of individual phenolic compounds (IPC) in OS starch films was significantly higher compared to native counterparts, showing increases of 35 %, 83 % and 20 % for films with bee pollen, bee bread, and propolis, respectively. The latter film exhibited the highest IPC, totaling 2204.4 mg/100 g. While OS starch did not affect the antimicrobial properties of the films, the incorporation of HBE significantly improved their ability to bacterial inhibition, with propolis showing the strongest effect. Despite reduced optical and sensory properties of OS films, OS starch complexes with bee bread and propolis show great potential for food packaging.

Influence of molarity on the structural, optical, photocatalytic and electrochemical properties of CoMn₂O₄ thin films fabricated by spray pyrolysis

Influence of molarity on the structural, optical, photocatalytic and electrochemical properties of CoMn₂O₄ thin films fabricated by spray pyrolysis

Annealing-Induced Phase Transformation in Vapor Deposited Tellurium Dioxide Thin Films and Its Structural, Chemical Analysis

Tellurium dioxide (TeO2) thin films were synthesized by thermal vacuum deposition on glass substrate and samples were annealed from 250°C to 400°C at 50°C interval. The annealing was found to have a significant impact on the structural, optical, and electrical properties of TeO2 thin films. X-ray diffraction spectra (XRD) revealed an increase in crystallite size and corresponding decrease in micro strain and dislocation density with increasing temperature. Annealed sample at 350 °C and 400 °C showed phase change from γ-TeO2 to β-TeO2 since β phase is thermodynamically favourable with greater free energy change. X-ray Photoelectron spectroscopy of all annealed sample confirm the improvement in formation of TeO2 from metallic Tellurium with air annealing. The XPS analysis also confirmed the existence of interstitial Oxygen, and its concentration increased at 400 °C. Raman spectroscopy employed to investigate the variation in vibrational modes with temperature and correlate these findings with other structural and chemical analyses. Photoluminescence study of TeO2 thin films reveals evolution of defect states with annealing temperature. Decrease in intensity of defect-related emissions (green, near-IR) suggests improved crystallinity which was in turn supported by the disappearance of low-level defect peaks upon annealing.

Effects of Tb(NO3)3 salt on the structural characteristics, optical, and radiation shielding properties of (PVA-PVP- PEG) polymeric composite films

Effects of Tb(NO3)3 salt on the structural characteristics, optical, and radiation shielding properties of (PVA-PVP- PEG) polymeric composite films

Consequence of Post-Annealing on Optical, Structural and Electrical Properties of Cadmium Telluride Thin Films for Solar Cells Applications

Consequence of Post-Annealing on Optical, Structural and Electrical Properties of Cadmium Telluride Thin Films for Solar Cells Applications

Structural and optical properties of CdO thin films deposited by spray pyrolysis technique

Structural and optical properties of CdO thin films deposited by spray pyrolysis technique

Fabrication of PMMA/SiO2 nanocomposite thin films: Optical and microwave radiation shielding properties

Incorporating SiO2 nanoparticles (SNPs) into Poly(methyl methacrylate) (PMMA) matrices can significantly enhance the optical and microwave shielding properties of nanocomposite thin films. In this study, PMMA/SiO2 nanocomposite thin films (PSNTFs) with varying concentrations of SNPs (1–10[Formula: see text]wg%) were fabricated using the solution casting method. The morphology of the films was characterized via scanning electron microscopy (SEM), revealing SNP sizes between 11.90[Formula: see text]nm and 16.66[Formula: see text]nm. Optical absorption, extinction coefficient and optical conductivity were studied in the ultraviolet-visible (UV-Vis) spectrum, showing a marked dependence on nanoparticle concentration. Additionally, microwave radiation shielding properties were evaluated, highlighting the potential application of these composites in electromagnetic interference (EMI) shielding. The results suggest that increasing SNP content improves optical and shielding efficiency, positioning these materials as promising candidates for advanced optoelectronic and microwave shielding applications.

Copper precursor-driven variations in structural, optical and electrical properties of SILAR-deposited CTS thin films

Abstract This pioneering study elucidates, for the first time, the profound impact of copper precursors (copper acetate, copper sulfate, and copper chloride) on the structural, optical, and electrical properties of Copper Tin Sulfide (CTS) thin films synthesized via successive ionic layer adsorption and reaction (SILAR) deposition. Comprehensive characterization using x-ray diffraction (XRD), cross-sectional scanning electron microscopy (SEM), atomic force microscopy (AFM), Fourier transform infrared (FTIR) spectroscopy, and electrical and optical measurements revealed significant variations in crystallite size (74.9–84.4 nm), film thickness (1.235–4.75 μm), and conductance (3.2–4.7 × 10−11 S). Notably, copper acetate-derived films exhibited enhanced surface morphology, whereas copper chloride-derived films demonstrated exceptional optoelectronic properties, including a maximum bandgap energy of 3.7 eV, highest conductance of 4.7 × 10−11 S, and unique optical characteristics, such as zero transmittance below 300 nm, low absorption above 300 nm, and a balanced absorption profile, rendering them suitable for photovoltaic cells, optical sensors, and UV-blocking applications. These results demonstrate the critical influence of copper precursors on CTS thin film properties, paving the way for tailored material design and enhanced device performance, with significant implications for the development of efficient and sustainable photovoltaic technologies.

Narrow-bandgap titanium sesquioxide with resonant metasurfaces for enhanced infrared absorption

We report on the structural, chemical, and optical properties of titanium sesquioxide Ti2O3 thin films on single-crystal sapphire substrates by pulsed laser deposition. The thin film of Ti2O3 on sapphire exhibits light absorption of around 25%–45% in the wavelength range of 2–10 μm. Here, we design an infrared photodetector structure based on Ti2O3, enhanced by a resonant metasurface, to improve its light absorption in mid-wave and long-wave infrared windows. We show that light absorption in the mid-wave infrared window (wavelength 3–5 μm) in the active Ti2O3 layer can be significantly enhanced from 30%–40% to more than 80% utilizing a thin resonant metasurface made of low-loss silicon, facilitating efficient scattering in the active layer. Furthermore, we compare the absorptance of the Ti2O3 layer with that of conventional semiconductors, such as InSb, InAs, and HgCdTe, operating in the infrared range with a wavelength of 2–10 μm and demonstrate that the absorption in the Ti2O3 film is significantly higher than in these conventional semiconductors due to the narrow-bandgap characteristics of Ti2O3. The proposed designs can be used to tailor the wavelengths of photodetection across the near- and mid-infrared ranges.

Annealing Effect on Linear and Ultrafast Nonlinear Optical Properties of Bi2Te3 Thin Films.

In recent years, the fabrication of materials with large nonlinear optical coefficients and the investigation of methods to enhance nonlinear optical performance have been in the spotlight. Herein, the bismuth telluride (Bi2Te3) thin films were prepared by radio-frequency magnetron sputtering and annealed in vacuum at various temperatures. The structural and optical properties were characterized and analyzed using X-ray diffraction, scanning electron microscopy, X-ray photoelectron spectroscopy, spectroscopic ellipsometry, and UV/VIS/NIR spectrophotometry. The third-order optical nonlinearities of Bi2Te3 thin films were investigated using the Z-scan technique, employing a 100 fs pulse width at an 800 nm wavelength. It is found that the crystallinity and the average grain size of the films increase with the annealing temperature. Meanwhile, the extinction coefficient of the annealed films increased, accompanied by a redshift in the optical bandgap. All samples exhibit pronounced saturable absorption and self-focusing behaviors. The nonlinear absorption coefficient and nonlinear refractive index of Bi2Te3 films annealed at 300 °C were found to be 2.44 times and 1.85 times higher than those of the as-deposited films, respectively. These findings demonstrate that annealing treatment is an effective approach to tuning the crystalline structure and linear optical properties of Bi2Te3 films while simultaneously enhancing their nonlinear optical performance.

Optical, structural, and vibrational properties of In2S3 thin films by sputtering-RF for applications in optoelectronics devices

Abstract Experimental results on the crystalline orientation properties, energy band gap, and Raman vibrational modes of Indium Sulfide (In2S3) thin films grown by Sputtering in Radio Frequency mode are presented. The In2S3 thin films were grown at 25, 200, and 300°C; thereafter the samples were thermally annealed in air for 30 min at 450°C, in order to improve their crystalline and physical properties. Energy dispersive X-ray spectroscopy results showed that the β-In2S3 crystallographic phase became predominant as the substrate temperature increased. For the optical transmittance spectra, it was observed that the deposited In2S3 thin films at 300°C and with thermal annealing showed an increase in their band gap energy of nearly 60 meV. The direct energy band gap of In2S3 films varied in the range of 2.76–2.82 eV. The scanning electron microcopy image and elemental analysis shows a better morphology, and an increase in O and Sn when the In2S3 samples were subjected to thermal annealed and the substrate temperature increased, respectively. Photoluminescence spectra were obtained at room temperature and showed two emission bands around 1.75 (709 nm) and 2.35 eV (527 nm), one related to interstitial indium donor sites (Ini) and oxygen acceptor vacancies (OVs), and the second to an emission band corresponding to the transition sulfur donor-indium acceptor. As the substrate temperature increased and thermal annealing of In2S3 was performed, the 1.75 eV emission bands increased in intensity with respect to the 2.35 eV band. From the Raman measurements, it was observed that the vibrational peaks were better defined as the substrate temperature increased and In2S3 underwent thermal annealing. In addition, to study the spinel-like defect structure, the peaks corresponding to the five main vibrational modes of In2S3 were identified as the Alg mode, Eg mode, and three modes of the F2g.

Analysis of Optical Thin-films: Towards Lower Reflectivity for High Performance Solar Cells and Modern Photonic Devices Applications

Recently, optical thin-films with lower reflectivity have attracted much interest for their suitability in high performance thin-film solar cells and various modern photonics devices, such as electronic display panels touchscreens, smart optical glass windows, spectacles frames, super-compact camera lenses, laser systems and optical fiber communications since lowering reflectivity coating improves the device performances. However, obtaining reduced reflectance from this arrangement remains challenging issue. As the film optical properties, such as the absorbance, reflection and transmission of particular wavelength of electromagnetic radiation can be carefully controlled by optimizing thin-film fabrication materials as well as structures, there is a lot of research scope in optimizing device reflectivity by assessing various film- and substrate materials as well as their thicknesses. Therefore, in this study, the reflectance performances of optical thin-films were characterized for obtaining lower reflectivity for various types of modern photonics applications. To obtain this, three novel optoelectronic materials InGaAs, CdTe and CsPbBr<sub>3</sub> for film layer<sub>, </sub>three widely used substrate materials glass, Al<sub>2</sub>O<sub>3 </sub>and steel as well as various thicknesses of film layer were evaluated. Reflectance studied of the thin-films for the three film materials have been clarified that CsPbBr<sub>3 </sub>is the best among these three film materials to be used for reducing the light reflection of the thin-film. Lower reflectivity of thin-films on glass substrate suggested that glass is better than both Al<sub>2</sub>O<sub>3 </sub>and steel as substrate in high efficiency thin-film solar cells and various photonics devices. In addition, evaluation of reflectance for various film thicknesses showed that ultra-thin film layer is superior for reducing the reflection of solar energy by thin-film structure. We have therefore proposed that thin-film with the combination of CsPbBr<sub>3</sub> based ultra-thin film layer on glass substrate would be one of the best possible solutions for reducing reflectivity of solar cells and various photonics devices, thereby for possibly increasing the performance efficiency. This research result would be very beneficial for the development of renewable energy and photonics based nanotechnology, thereby play a significant role for reducing global energy crisis and green-house gas emission concurrently and sustainably in the modern world.

Effect of annealing temperature on the structural and optical properties of SnO2 thin films elaborated by sol-gel technique

In this study, the influence of annealing temperature on the structural and optical properties of SnO2 thin films was investigated. SnO2 thin films were prepared by sol–gel deposition on glass substrates at room temperature and then annealed at different temperatures (300, 400 and 500°C) in air for two hours. The obtained films were characterized by Raman spectroscopy and UV–Vis spectrophotometry techniques. A single-phase rutile structure was revealed by Raman spectroscopy analysis. The optical measurements have shown that all the films have a high transparency (75-85%) in the visible spectral range, and the optical band gap increases from 3.68 to 3.89 eV with increasing annealing temperature.

Optical and transport properties of NbN thin films revisited

Optical and transport properties of NbN thin films revisited

The Structural and Optical Properties of Polycrystalline Copper Oxide Thin Films Synthesized Using the SILAR Technique

The Structural and Optical Properties of Polycrystalline Copper Oxide Thin Films Synthesized Using the SILAR Technique

The Influence of Molarity on the Optical and Electrical Properties of Fluorine-Doped Tin Oxide Thin Films Using Spray Pyrolysis Technique

The Influence of Molarity on the Optical and Electrical Properties of Fluorine-Doped Tin Oxide Thin Films Using Spray Pyrolysis Technique