Optical Properties Of Thin Films Research Articles

Thin Film Deposition and Optical Properties of Cs-Cu-I System Via Mist Deposition with Various Precursor Compositions

Thin Film Deposition and Optical Properties of Cs-Cu-I System Via Mist Deposition with Various Precursor Compositions

Preparation and Optical Properties of Thin Films of ZnIn2S4 (I, III) Polytype

Preparation and Optical Properties of Thin Films of ZnIn2S4 (I, III) Polytype

Enhancement of crystallinity and the optical properties in gamma irradiated and thermally annealed cobalt doped MgTiO3 thin films

We report the crystal structure, surface morphology and optical properties of gamma (γ) irradiated, and thermally annealed cobalt (5 %) doped magnesium titanate thin films. Mg0.95Co0.05TiO3 (MCT) thin films were fabricated on quartz substrates by Radio Frequency magnetron sputtering while substrate temperature was maintained at 300 °C. Firstly, the as-prepared MCT thin films were irradiated by 1.33 MeV 60Co γ – rays with varying doses in the range of 0 – 125 kGy with the intervals of 25 kGy and post-annealing process at 700 °C. The X-ray diffraction pattern of irradiated thin films is amorphous, whereas annealed films are crystalline, which are refined with the Rietveld refinement method by considering the R3¯space group. Dominated crystallite size (39 nm) with low strain is identified for the samples exposed at 75 kGy. In addition to the γ-irradiation of 75 kGy, the optical characteristics revealed that an enhanced bandgap (∼ 4.27 eV) and refractive index (2.26) had been observed for an annealed sample as compared with the bandgap (∼ 3.68 eV) and refractive index (2.10) of as-deposited sample. The influence of γ-irradiation dose and annealing on MCT thin films' structural and optical properties has been discussed. This study demonstrates that the γ–ray irradiated MCT films are potential candidates for anti-reflection coating applications.

Synthesis and Characterization Studies of Pure and Co Doped ZnO Nano Thin Films

General Background: Thin-film technology is pivotal in advancing modern optoelectronic devices due to its ability to tailor material properties at the nanoscale. Specific Background: Zinc oxide (ZnO) and cobalt oxide (CoO) are prominent materials in this field, with doping techniques such as cobalt incorporation offering potential enhancements in film properties. Knowledge Gap: The impact of cobalt doping on the structural and optical properties of ZnO thin films remains inadequately explored, particularly concerning varying doping concentrations. Aims: Aims to elucidate the effects of cobalt doping on ZnO thin films' structural and optical characteristics, with concentrations of Zn0.6Co0.4O and Zn0.8Co0.2O compared to pure ZnO and CoO films. Results: Thin films were prepared via spin coating on glass substrates at 3000 rpm for 30 seconds. X-ray diffraction analysis revealed that pure ZnO films possess a hexagonal polycrystalline structure, whereas CoO films exhibit a cubic structure. Doping with cobalt resulted in a decrease in peak intensity at the (111) orientation and an increase in grain size. Optical measurements indicated enhanced transmittance and modified absorbance spectra with increased cobalt content, showing maximum absorbance at short wavelengths and diminished values in the visible region. Reflectivity increased with photon energy before decreasing at higher energies. Novelty: Cobalt doping significantly alters both structural and optical properties of ZnO films, with distinct changes in lattice constants, grain size, and optical behavior, suggesting a potential route for optimizing ZnO-based materials. Implications: Cobalt-doped ZnO films hold promise for improved performance in optoelectronic applications, such as solar cells and sensors, necessitating further research into diverse doping strategies to fully harness their technological potential. Highlights: Cobalt doping alters ZnO thin films' structural and optical properties. Spin coating method used at 3000 rpm for 30 seconds. Enhanced optical properties suitable for optoelectronic applications. Keywords: Thin films, Zinc oxide, Cobalt doping, Optical properties, X-ray diffraction

Influence of choline chloride pH adjuster on physical and optical properties of CuInSe2 thin films by CBD

We concentrate on low-cost thin film solar cells with the help of choline chloride acting as a pH adjuster because copper ternary material compounds and their alloys have become more and more lavish over the past 20 years. Chemical Bath Deposition (CBD) is used to produce copper indium selenium (CuInSe2) thin films on glass substrates while a pH adjuster is present. The micro structural and elemental properties are studied using X-ray diffraction (XRD), Raman, Scanning Electron Microscope (SEM), and Energy Dispersive Spectroscopy (EDS). The optical studies of CuInSe2 thin films are done using a UV–Vis–NIR spectrometer. XRD and Raman spectra shows that the CIS thin films deposited in the sequence of Glass/In/Se/Cu2Se/Se (labeled as CISB) and annealed at 400 °C (CISB400) contains all the peaks corresponding to the chalcopyrite CuInSe2. From the EDS measurements it was noted that the selenium to metal ratio (Se/Cu + In) for all the samples changes with temperature. It is worth to note that the film thickness decreases with a decrease in the pH of choline chloride which results a change in the optical band gap of the films. The optical properties of these thin films are greatly influenced by adjusting pH and it gives better results for optoelectronic devices with a sustainable UV filter which absorbs more in ultraviolet vicinity. The energy gap (Eg) values of the CISB samples were determined and is found to be suitable for photovoltaic conversion process.

Tuning the optical properties of transparent ZIF-8 thin films by adjusting the crystal morphology

Optical properties are the most significant properties of optical thin films, which determine its application in optical and photoelectric devices. Designable optical properties are the most challenging goals in optical material engineering. Recently, Metal-organic framework (MOF)-based optical thin films have attracted increasing attention due to their novel optical properties, especially their modular design, which allows fine-tuning of the relevant properties. In this work, a strategy for tuning the optical properties of MOF-based thin films is developed, which is realized by adjusting MOF crystal morphology. A commonly used MOF, ZIF-8 (zeolitic imidazolate framework-8), is selected as the research model. The morphology of ZIF-8 nanocrystal is adjusted using a surfactant/end-capping agent modulation method. The surfactant/end-capping agents are absorbed onto different crystal planes of ZIF-8, slowing the growth of the crystal planes and causing the formation of ZIF-8 crystals with different morphologies. Six different morphologies of ZIF-8 crystals are successfully synthesized in the presence of different amounts of CTAB and/or TRIS: nano-spherical, rhombohedral dodecahedron, nano-cubic, rough octahedron, flake-shaped and hexapod-like morphology. Then, the corresponding ZIF-8 thin films with different crystal morphologies are prepared via spin-coating. The optical properties of the thin films are investigated using UV–vis spectroscopy and ellipsometry in detail. The results indicate that the film with rough octahedron morphology has the best transmittance, reaching 93.35 % at 581 nm. As a key optical parameter of the film, its refractive index can be adjusted between 1.27 and 1.54. The success of tuning of the optical properties of MOF optical thin films by adjusting the crystal morphology will make it meet the different required optical properties in various optical and photoelectric devices.

Cu-doped NiO thin film's structural, optical, and electrical properties and its negative absorption behaviour in the Infra-Red region

NiO undoped and Cu-doped thin films on FTO-coated glass (fluorine-doped tin oxide) are prepared by employing the sol-gel spin coating method. The Cu-doping effect was observed in all the characterized reports such as absorption, transmittance, field emission scanning electron microscope (FESEM), Grazing Incidence X-ray Diffraction (GIXRD), photoluminescence (PL), Raman spectra, current-voltage measurement (IV), and X-ray photoelectron spectroscopy (XPS). Enhancement in electrical conductivity due to Cu doping and IR illumination has been found. Band gap can also be tuned by varying doping concentrations. One new phenomenon called negative absorption (NA) has been found while investigating the optical properties in the infrared (IR) region for both undoped and Cu-doped NiO on the FTO substrate, which opens a new door for advanced research. The multifarious properties of NiO thin films offer various applications in many different fields.

Effect of hydrogen flow rate on properties of silicon oxycarbide thin films via hot wire chemical vapor deposition

AbstractThis study explores the impact of hydrogen flow as a carrier gas on silicon oxycarbide thin films produced via hot wire chemical vapor deposition (HWCVD) using tetraethyl orthosilicate as a precursor. Systematically varying the hydrogen flow rates, the influence on thin film composition, microstructure, and optical properties is investigated. Employing diverse characterization techniques, such as X‐ray diffraction, field‐emission scanning electron microscopy (FE‐SEM), energy‐dispersive X‐ray spectroscopy, Fourier‐transform infrared (FTIR), X‐ray photoelectron spectroscopy (XPS), ellipsometry, and photoluminescence (PL) spectroscopy, it is revealed that there is a correlation between hydrogen flow rate and thin film elemental composition. Higher hydrogen flow rates result in increased silicon content and reduced contributions of oxygen and carbon. FE‐SEM images show agglomerates with improved homogeneity at higher flow rates. FTIR spectra highlight distinctive vibrational modes, including Si–H bonds. XPS confirms the emergence of Si–H bonds at elevated hydrogen flow rates. Ellipsometry indicates increased thickness and refractive index. PL spectra exhibit a broadband across the visible spectrum, influenced by hydrogen‐related defects and electronic transitions. This study provides findings for optimizing HWCVD parameters to tailor thin films for specific applications, emphasizing the important role of hydrogen flow as a carrier gas.

Effect of Mo and W co-doping on optical, morphological, electrical and electrochemical properties of Co3O4 thin film

In this study, it was aimed to produce cobalt oxide (Co3O4) thin films with improved optical, electrical, and electrochemical properties for device applications with a simple and low-cost method. Mo, W, and dual Mo and W at the ratio 10 wt% of Co3O4 were added into the solutions. The prepared solutions were coated on glass substrates by spin coating method. The produced thin films' structural, morphological, optical, electrical, and electrochemical properties were examined. As a result of doping, the optical, morphological, conductivity, and electrochemical properties of Co3O4 thin films improved and more stable structures were formed. The Mo and W co-doping provided the most improvement in the properties of the Co3O4 thin film. The results obtained showed that the Mo and W co-doped Co3O4 thin film is a potential candidate for highly efficient electrochemical applications.

Numerical ellipsometry: Artificial intelligence for rapid analysis of indium tin oxide films on silicon

Ellipsometry is a well-known material analytical method widely used to measure thickness and optical properties of thin films and surfaces across a wide range of industrial and research applications including critical dimensions in chipmaking. The method employs the fact that light undergoes a change in polarization state upon reflection from or transmission through a material. The desired properties of the surface structure are related to measurements by the electromagnetic models expressed by Maxwell’s equations as well as models of material properties. The work here demonstrates the use of artificial intelligence in the form of a multilayer perceptron artificial neural network to apply the electromagnetic model. The reflecting surface examined here is composed of indium tin oxide (ITO) films approximately 400 nm in thickness deposited on silicon substrates. Solutions are provided by 299 artificial neural networks, one per wavelength from 210 to 1700 nm across which ITO exhibits transparent as well as absorbing characteristics. Thus, it serves as a proxy for a wide range of other materials. To train the network, simulated measurements are computed at two thicknesses which differ randomly by 1–6 nm and at three different incidence angles of 55°, 65°, and 75°. Following training, results are obtained in less than one second on a conventional desktop computer.

Plasma emission spectroscopy and optical properties of reactive-sputtered silicon oxynitride films

Silicon oxynitride (SiO x N y ) thin films were synthesized via reactive direct current magnetron sputtering under different reactive gas mass flow ratios (O2:N2) and discharge powers. The process was monitored by optical emission spectroscopy (OES), while spectroscopic ellipsometry was used to characterize the optical properties of the thin films and deposition rates. In this work, the plasma generated under different deposition parameters is analyzed by monitoring the emission lines of different species (Si I, Ar I, O2, and N2) and these results are then correlated with the corresponding target poisoning process and the optical properties of the grown thin films. According to the spectral analysis, the emission lines proved to be sensitive to the synthesis process as it was possible to differentiate deposition variations when other parameters remained unchanged. Furthermore, similar plasma conditions determined via the emission of different species were found to produce consistent thin film optical properties and vice versa. OES showed to be an effective method of monitoring and controlling the deposition of SiO x N y thin films with specific compositions.

Fabrication and investigation of PMMA-doped 1, 3, 5-triphenylbenzene (TPB) thin film's structural, optical, and electrical properties for optoelectronic devices

In this experimental work, triphenylbenzene/polymethylmethacrylate (TPB/PMMA) based thin films were deposited using a spin coating to examine their structural, optical, and electrical properties. The deposited thin film has a crystalline nature with an average crystalline size of 27.12 nm, and a dislocation density of 7.1 × 10−4 nm−2. The absorption spectra of TPB, PMMA, and TPB-PMMA films lie in the range of 200 nm–500 nm with an optical bandgap of 3.85 eV, for TPB-PMMA. The PL spectra of pure TPB thin film give a constant emission at 360 nm, which is independent of the excitation wavelength in the range of 310 nm–340 nm. The excitation-dependent behaviors for both pure TPB and TPB-PMMA were observed in terms of intensity that first increases and gives maximum intensity for the excitation wavelengths of 328 nm and 315 nm, respectively. From CIE coordinates, it was observed that the TPB-PMMA thin film gives a constant deep blue emission. The effect of TPB-PMMA percentage was examined with the help of IV studies, and at 20 % TPB: PMMA, the presence of more TPB molecules was observed resulting in a smaller distance between molecules and a larger number of available paths for current flow. Further, with a rise in temperature from 303K to 353K, the thermal stability of the TPB-PMMA thin film was excellent, and it kept the ohmic behavior. The examined optical bandgap of TPB-PMMA thin film falls within the range that is appropriate for OLEDs with emission in the blue region. In addition, the excellent structural and electrical properties of TPB-PMMA make it a suitable candidate for optoelectronic devices.

Optical properties of thin films monitored in real-time at high gamma radiation doses using long period fiber gratings

In this work, we report an all-optical-fiber-based method to monitor in real-time the changes in thin film optical properties when exposed to harsh environments such as high doses of gamma radiation. The method is based on a long period grating (LPG) inscribed in a radiation resistant optical fiber, which is coated with a thin film to be analyzed. Due to impact of the environment on the film properties, the transmission spectrum of the LPG changes. To validate this methodology, we deposited oxides of various metals, i.e. aluminum (Al2O3), titanium (TiO2), and tantalum (Ta2O5), as well as a polymeric film, namely polystyrene (PS), on the LPG surface and measured the resonant wavelength shift induced by high doses of gamma exposure (dose rate of 2.3 kGy/h, up to a total dose of 46 kGy). The changes could be observed in real-time up to maximum reached dose and during the recovery period. The results are significantly dependent on thin film material. Among the oxides, TiO2 thin film demonstrated the highest susceptibility to irradiation, whereas Al2O3 exhibited the least impact. Additionally, a good recovery potential for Ta2O5 thin film was observed, hinting at its promising application in dosimetry. Conversely, the PS film exhibited a permanent effect induced by irradiation. This is the first real-time experimental study of the impact of high dose gamma radiation on thin film optical properties using a universal optical-fiber-based device. The findings pave the way for assessing radiation hardness of thin film materials or utilizing such a method to optimize material treatment involving ionizing radiation.

Synthesis and Optical Properties of Erbium-Doped Sodium Silicate in Sol-Gel Matrix

In this study, we investigated how the concentration of erbium (0.0, 1, 2 mol% Er) affects the structural and optical properties of thin films made from sol-gel sodium silicate doped with erbium nitrate, thermally treated at 250 °C. Through systematic investigation, we explore the structural evolution and optical behavior of the thin films across varying Er3+ concentrations. The sol-gel demonstrated effective capabilities for substantial concentrations of Er3+ oxides through doping at lower calcination temperatures. The spectroscopic characteristics were studied using visible-near infrared spectroscopy (UV–vis–NIR), transmission electron microscopy, and Fourier transform infrared spectroscopy. Increasing the Er ratio decreased both the transmission and the energy band gap (3.6–3.34 eV) of the films while the absorption peak increased. The obtained results suggest that Er3+ activators demonstrate advantageous optical properties in the evaluated sodium silicate glass matrix. With the introduction of Er, optical transmittance ranges from 85 to 55% in the visible and near-infrared (NIR) regions, highlighting their advantageous characteristics. This research contributes to advancing the understanding of erbium-doped thin films for potential applications in optoelectronic devices and photonics.

Effect of Mesoporous Silica as a Solid Precursor on the Properties of Silicon Oxycarbide Thin Films via Hot Filament Chemical Vapor Deposition

AbstractThis study investigates the impact of mesoporous silica tablets on the synthesis and properties of silicon oxycarbide thin films produced via Hot Filament Chemical Vapor Deposition. Results reveal significant variations in composition and cluster morphology, influenced by the introduction of mesoporous silica tablets. The study demonstrates controlled deposition, consistent synthesis, and the substantial impact of mesoporous silica tablets on the composition, structure, and optical properties of thin films. These findings offer new possibilities for tailor design applications in electronics, optics, and sensors.

Silicon nitride thin-films deposited by radiofrequency reactive sputtering: Refractive index optimization with substrate cooling in a nitrogen-rich atmosphere

Silicon nitride (SiN) is widely used as a core material in optical waveguides due to its optical properties. The deposition of SiN thin-films by radiofrequency (RF) reactive sputtering is commonly used in low-temperature processes, where the thin-films optical properties can be optimized by controlling the deposition parameters (sputtering power, gases ratio, etc.). This work presents the deposition of several SiN thin-films by RF reactive sputtering with different sputtering powers (ranging from 180 W to 300 W), with a nitrogen-argon ratio of 16:4, and performing substrate cooling in a nitrogen-rich atmosphere immediately after deposition, consisting in keeping the substrate under 16 sccm of nitrogen until it reaches 25 °C. The refractive indices of the SiN thin-films were assessed through ellipsometry, obtaining a maximum refractive index of 1.906 at 400 nm. SiN thin-films were also analyzed by energy-dispersive spectroscopy (EDS) and atomic force microscopy (AFM).

Utilizing Gold Nanoparticle Decoration for Enhanced UV Photodetection in CdS Thin Films Fabricated by Pulsed Laser Deposition: Exploiting Plasmon-Induced Effects.

UV sensors hold significant promise for various applications in both military and civilian domains. However, achieving exceptional detectivity, responsivity, and rapid rise/decay times remains a notable challenge. In this study, we address this challenge by investigating the photodetection properties of CdS thin films and the influence of surface-deposited gold nanoparticles (AuNPs) on their performance. CdS thin films were produced using the pulsed laser deposition (PLD) technique on glass substrates, with CdS layers at a 100, 150, and 200 nm thickness. Extensive characterization was performed to evaluate the thin films' structural, morphological, and optical properties. Photodetector devices based on CdS and AuNPs/CdS films were fabricated, and their performance parameters were evaluated under 365 nm light illumination. Our findings demonstrated that reducing CdS layer thickness enhanced performance concerning detectivity, responsivity, external quantum efficiency (EQE), and photocurrent gain. Furthermore, AuNP deposition on the surface of CdS films exhibited a substantial influence, especially on devices with thinner CdS layers. Among the configurations, AuNPs/CdS(100 nm) demonstrated the highest values in all evaluated parameters, including detectivity (1.1×1012 Jones), responsivity (13.86 A/W), EQE (47.2%), and photocurrent gain (9.2).

Optical and morphological properties of DCM thin films co-doped of Znq2 by PVD: Theoretical and experimental investigations

In this article, new experimental results of the morphological and optical properties of thin films of 4-(dicyanomethylene)-2-methyl-6-(4-dimethylaminostyryl)-4H-pyran co-doped by 8-hydroxyquinoline zinc (Znq2) for different concentrations were presented. The physical vapor deposition in a high vacuum was used to create the thin films on glass substrates with a thickness of 100 nm. The morphological properties of the samples were identified using the Atomic Force Microscopy (AFM) apparatus in tapping mode. TEM images show amorphous structures. The phase composition of the samples was assessed using FTIR methods. The Tauc plot approach was used to examine the measured transmittance spectra in order to estimate the energy gap. Analysis of the results showed that the co-doping of DCM thin film by Znq2 influenced the structural and optical properties of the samples. To evaluate the experimental results found, theoretical calculations based on the maximum one-photon absorption (OPA) wavelengths of DCM and Znq2 have been first measured through the UV–Vis spectral technique. Then, the experimental conclusions on values for DCM and Znq2 have been compared with their corresponding simulation data procured from the time-dependent self-consistent-field (TD-SCF) computation utilizing the density functional theory (DFT) at B3LYP/6-311G(d,p) level. Besides, we have explored the first and second frontier molecular orbitals (MOs) for title compounds and their energy gaps via the DFT procedure. The calculations of maximum OPA wavelengths and the highest occupied molecular orbital (HOMO) and the lowest unoccupied molecular orbital (LUMO) contributions on both molecules have also been crosschecked with the results of already published data in the literature.

Structural and Optical Properties of Thin Film β-Ta upon Exposure to Hydrogen to Asses Its Applicability as Hydrogen Sensing Material

Structural and Optical Properties of Thin Film β-Ta upon Exposure to Hydrogen to Asses Its Applicability as Hydrogen Sensing Material

Thermal and optical properties of P3HT:PC70BM:ZnO nanoparticles composite films

The results of studies on the influence of zinc oxide nanoparticles (ZnO-NPs) on the structural, thermal and optical properties of thin films of mixtures of phenyl-C71-butyric acid methyl ester (PCBM) with poly[3-hexylthiophene] (P3HT) of various molecular weights are described in this article. The structural properties of the layers of: polymers, mixtures of polymers with fullerenes and their composites with ZnO-NPs were investigated using X-ray diffraction. Whereas their glass transition temperature and optical parameters have been determined by temperature-dependent spectroscopic ellipsometry. The presence of ZnO-NPs was also visible in the images of the surface of the composite layers obtained using scanning electron microscopy. These blends and composite films have also been used as the active layer in bulk heterojunction photovoltaic structures. The molecular weight of P3HT (Mw = 65.2; 54.2 and 34.1 kDa) and the addition of nanoparticles affected the power conversion efficiency (PCE) of the obtained solar cells. The determined PCE was the highest for the device prepared from the blend of P3HT:PCBM with the polymer of the lowest molecular weight. However, solar cells with ZnO-NPs present in their active layer had lower efficiency, although the open-circuit voltage and fill factor of almost all devices had the same values whether they contained ZnO-NPs or not. It is worth noting that thermal studies carried out using temperature-dependent ellipsometry showed a significant effect of the presence of ZnO-NPs on the value of the glass transition temperature, which was higher for composite films than for films made of a polymer-fullerene blend alone.