Optical Properties Of Films Research Articles

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

The Effect of H+ Fluence Irradiation on the Optical, Structural, and Morphological Properties of ZnO Thin Films.

Polycrystalline zinc oxide (ZnO) thin films were deposited on soda-lime glass substrates using the chemical spray pyrolysis method at 450 °C. The samples were irradiated with 8 keV H+ ions at three different fluences using a Colutron ion gun. The effects of the irradiation on the structural, morphological, and optical properties were studied with different techniques, including Rutherford Backscattering Spectrometry (RBS), X-ray diffraction (XRD), Scanning Electron Microscopy (SEM), and Ultraviolet and Visible Spectroscopy (UV-Vis). The results show that ion irradiation enhances crystallinity, narrowing the optical band gap. The changes in transmittance are related to defect formation within the material, which acts as light absorption and re-emission centers. A shifting of the film's preferred growth orientation to the c-axis and changing the grain morphology and size distribution was detected. We observed an increase in the lattice parameters observed after irradiation, suggesting an expansion of the crystalline structure due to ions incorporation and defects within the ZnO crystal lattice. The morphological study shows an increase in the average size of the large particles after irradiation. This change is attributed to the emergence of defects and nucleation centers during irradiation. The average size of small particles remained relatively constant after irradiation, suggesting that small particles are more stable and less susceptible to external influences, resulting in fewer changes due to irradiation.

Performance of Cu-doped V2O5 thin film as a hole transport layer in perovskite-based solar cells

Abstract Herein, the performance of Cu-doped V2O5 thin film as a hole transport layer (HTL) in inverted planar (p-i-n) perovskite solar cells was reported. The structural, optical, morphological, and electrical properties of Cu-doped V2O5 thin films, with varying Cu concentrations, were analyzed using x-ray photoelectron spectroscopy, UV-Vis spectrophotometry, atomic force microscopy, Kelvin probe force microscopy, and a four-point probe system. The sheet resistance of the V2O5 HTLs decreased significantly with Cu doping, leading to an increase in the devices’ short-circuit current, which depended on the Cu concentration in the V2O5 thin films. It was demonstrated that V2O5 thin films produced using a low-temperature process can serve as a HTL in p-i-n perovskite solar cells. Furthermore, Cu doping in V2O5 thin films was shown to enhance the power conversion efficiency of the devices.

Nucleation, Electronic, and Optical Properties of Bi Thin Films Electrodeposited on n‐Si(111) Substrate

This study investigates the electrochemical nucleation and growth mechanisms of bismuth on a monocrystalline n‐Si(111) substrate from an acidic nitrate solution. It also examines the electrical and optical properties of the electroplated films. The qualitative analysis of the experimental current transients reveals a strong agreement with instantaneous nucleation on active sites and three‐dimensional diffusion‐controlled growth. Electrochemical kinetic parameters are derived using the Mirkin–Nilov–Heerman–Tarallo model, which is employed to fit the experimental curves. Electrochemical impedance spectroscopy and Mott–Schottky analysis are used to assess the electronic characteristics of the materials. Scanning electron microscope observations show a uniform, smooth, and continuous deposit. X‐ray diffraction analysis indicates a high texture along the [012] direction of the rhombohedral crystal structure in thin bismuth films with different thicknesses (118, 318, and 611 nm). UV–visible spectroscopy is employed to investigate the optical characteristics of the Bi/Si surface in the 200–1100 nm wavelength range. The study demonstrates that the thickness of the bismuth film affects the absorption response of the Bi/Si heterojunction, showing a notable increase in absorption in the visible and infrared ranges. Furthermore, it is found that the photoluminescence properties of the Bi/Si heterojunction are improved in the visible and infrared ranges.

Impact of Sulfur Concentration on the Magnetic and Electrical Characteristics of ZnMnO Thin Films

Influence of the sulfur doping on the structural, optical, electrical and magnetic properties of ZnMnO thin films fabricated using the ultrasonic spray pyrolysis technique was investigated. Our study reveals that increasing sulfur content leads to a noticeable shift in the band gap energy towards the red spectrum, an indicator of altered electronic states and potential for enhanced spintronic functionalities. The strong reduction in the band gap for the sulfur doped ZnMnO alloys is the result of the upward shift of the valence-band edge. As a result, the room temperature bandgap of ZnMnO1-xSx alloys can be tuned from 3.2 eV to 2.97 eV for x ≤ 0.2. The observed large bowing in the composition dependence of the energy bandgap arises from the anticrossing interactions between the valence-band of ZnO and the localized sulfur level above the ZnMnO valence-band maximum. The doping process significantly modifies the ferromagnetic properties, with an observed increase in Curie temperature correlating with higher sulfur concentrations. These changes are attributed to the increased free holes concentration, which facilitates a more robust exchange interaction between the magnetic ions. Additionally, the structural assessments via scanning electron microscopy confirm the uniform integration of sulfur into the ZnMnO matrix, resulting in distinct nanocrystalline formations. This study contributes to the understanding of doping mechanisms in semiconductor materials, especially for highly mismatched alloys, where the anions are partially substituted with isovalent atoms of considerably different size and/or electronegativity, offering insights into the tunability of their magnetic and electronic properties for potential future applications in spintronic devices.

Boron Trioxide-Assisted Post-Annealing Enables Vertical Oriented Recrystallization of Sb2Se3 Thin Film for High-Efficiency Solar Cells.

Crystallization process is critical for enhancing the crystallinity, regulating the crystal orientation of polycrystalline thin films, as well as repairing defects within the films. For quasi-1D Sb2Se3 photovoltaic materials, the preparation of Sb2Se3 thin films still faces great challenges in adjusting orientation and defect properties, which limits the device performance. In this study, a novel post-treatment strategy is developed that uses a low melting point B2O3 coating layer as a flux to drive the recrystallization of Sb2Se3, thereby regulating the micro-orientation of thermal evaporation-derived Sb2Se3 films and optimizing their electrical properties. Mechanistic investigations show that B2O3 exhibits stronger adsorption with (hk1) planes of Sb2Se3 to induce a vertical orientation growth of the film, while blocking the volatilization channels of Se and inhibiting Se vacancy defects by interacting with Sb2Se3. The Sb2Se3 film with [hk1] preferential orientation and suppressed deep-level defects promotes the effective transport of charge carriers in solar cells. As a result, the B2O3-treated device delivers a champion efficiency of 9.37% without MgF2 anti-reflection coating, which is currently the highest efficiency in Sb2Se3 solar cells achieved by thermal evaporation method. This study provides a new method and mechanism for regulating optical and electrical properties of low-dimensional inorganic thin films.

Optical and photoelectric properties of nanostructured SnS films obtained by spraying ink using a nanoparticle suspension

Abstract In this work, SnS films were prepared using spraying ink with a nanoparticle suspension. The average size of the synthesized nanoparticles was (18-20) nm. The structural, optical and photoelectric properties of SnS films were investigated using different characterization techniques. XRD and EDX results show that the investigated films exhibited an orthorhombic SnS phase with a composition close to the stoichiometry (CS/CSn = 0.99) and low level of microdeformation (ε = 1.8×10-3). In addition, the hexagonal SnS2 and tetragonal SnO2 phases were also observed. The presence of SnS and SnS2 phases is confirmed by Raman characteristics. The band gap of the SnS, SnS2, and SnO2 phases was determined using the novel ACFD method based on the analysis of the spectra of the first derivative of the absorption coefficient, which directly determines the energy of both band-to-band optical transitions and transitions involving defect`s levels. These results correlate very well with data obtained using photoconductivity spectra. The nature of the electronic optical transitions as well as the type and energy position of various defect levels were established. It was shown that the energy of direct and indirect band-to-band optical transitions of SnS compound correspond to 1.72 eV and 1.16 eV, respectively. At the same time, the band gap of SnS2 phase equal to 2.05 eV. The ionization energy of the acceptor (233 meV) and donor (100 meV) levels that determine the p- and n-type conductivity of SnS and SnS2 compounds, respectively were defined. Due to its properties, SnS films may be suitable for the development of novel effective solar cells with SnS absorber layers.

Effects of Substrate Temperature on Optical, Structural, and Surface Properties of Metal-Organic Vapor Phase Epitaxy-Grown MgZnO Films.

MgZnO possesses a tunable bandgap and can be prepared at relatively low temperatures, making it suitable for developing optoelectronic devices. MgxZn1-xO (x~0.1) films were grown on sapphire by metal-organic vapor phase epitaxy under different substrate-growth temperatures Ts of 350-650 °C and studied by multiple characterization technologies like X-ray diffraction (XRD), spectroscopic ellipsometry (SE), Raman scattering, extended X-ray absorption fine structure (EXAFS), and first-principle calculations. The effects of Ts on the optical, structural, and surface properties of the Mg0.1Zn0.9O films were studied penetratively. An XRD peak of nearly 35° was produced from Mg0.1Zn0.9O (0002) diffraction, while a weak peak of ~36.5° indicated MgO phase separation. SE measurements and analysis determined the energy bandgaps in the 3.29-3.91 eV range, obeying a monotonically decreasing law with increasing Ts. The theoretical bandgap of 3.347 eV, consistent with the SE-reported value, demonstrated the reliability of the SE measurement. Temperature-dependent UV-excitation Raman scattering revealed 1LO phonon splitting and temperature dependency. Zn-O and Zn-Zn atomic bonding lengths were deduced from EXAFS. It was revealed that the surface Mg amount increased with the increase in Ts. These comprehensive studies provide valuable references for Mg0.1Zn0.9O and other advanced materials.

Tailoring the optical properties of holey Si thin films

Abstract Si thin films with holes are composite materials with interesting optical properties that can be fabricated and modified by state-of-the-art Si process technologies. Adjusting the volumetric air fraction of these films allows control over their effective refractive indices. This work demonstrates a novel scalable method that combines charged sphere colloidal lithography (CSCL) and dry etching to pattern spatially disordered nanoholes in Si thin films. The method can also be adapted to dielectric materials other than silicon. We show controlled tuning of the effective refractive index by lateral dry-etching of the holes. Utilizing this process, a progressive widening of the average hole diameter was obtained, expanding from initial diameters of 60 nm and 100 nm to dimensions reaching 118 nm and 168 nm, respectively. Consequently, the refractive index of the holey films decreased to approximately 2.1 determined via ellipsometry and Bruggeman's model in the near-infrared (NIR) - mid-infrared (MIR) range, in contrast to the unstructured Si refractive index of 3.42. The systematic optical modification was also observed in the reflection spectra of the fabricated films using Fourier-transform infrared spectroscopy (FTIR). Dielectric holey thin films can be attractive for potential applications in MIR photonic devices such as filters and waveguides.

Influence of Ru-dopant on the structural, morphological, optical and electrical properties of NiO films

Influence of Ru-dopant on the structural, morphological, optical and electrical properties of NiO films

Evaluation of the optical, structural, morphological and electronic properties of Rb3Bi2I9 Perovskites films prepared by Sequential Evaporation

Evaluation of the optical, structural, morphological and electronic properties of Rb3Bi2I9 Perovskites films prepared by Sequential Evaporation