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Spectrophotometric Characterization of Thin Copper and Gold Films Prepared by Electron Beam Evaporation: Thickness Dependence of the Drude Damping Parameter
摘要： Copper and gold films with thicknesses between approximately 10 and 60 nm have been prepared by electron beam evaporation and characterized by spectrophotometry from the near infrared up to the near ultraviolet spectral regions. From near normal incidence transmission and reflection spectra, dispersion of optical constants have been determined by means of spectra fits utilizing a merger of the Drude model and the beta-distributed oscillator model. All spectra could be fitted in the full spectral region with a total of seven dispersion parameters. The obtained Drude damping parameters shows a clear trend to increase with decreasing film thickness. This behavior is discussed in the context of additional non-optical characterization results and turned out to be consistent with a simple mean-free path theory.
关键词： optical constants,gold,copper,ultrathin metal films,thickness dependence
更新于2025-11-21 11:01:37
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Ellipsometric study on optical properties of hydrogen plasma-treated aluminum-doped ZnO thin film
摘要： Aluminum-doped zinc oxide (AZO) thin films were prepared by radio frequency (RF) sputtering at room temperature, and then post-treated by hydrogen (H2) plasma at different durations. After H2 plasma treatment under the condition of 10 W, 200 °C and 3.0 Hours, the resistivity showed a dramatically decrease from 1.6 Ω cm to 3.4 × 10?3 Ω cm, while the transmittance at the wavelength of 550 nm was improved from 90.5% to 96.0%. The optical constants of H2 plasma-treated AZO thin films were detailed characterized by a varied angle spectroscopic ellipsometer. The results show that the refractive index n decreases in the entire measured wavelength range of 350–1100 nm, while the extinction coefficient k decreases in the short wavelength range and changes negligibly at the long wavelength range. These results can provide guidelines for the design and optimization of AZO thin film-based optoelectronic applications.
关键词： Resistivity,Spectroscopic ellipsometer,Transmittance,Optical constants,Hydrogen plasma treatment,Aluminum-doped zinc oxide
更新于2025-11-14 17:03:37
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Measurement of Optical Constants of TiN and TiN/Ti/TiN Multilayer Films for Microwave Kinetic Inductance Photon-Number-Resolving Detectors
摘要： We deposit thin titanium nitride (TiN) and TiN/Ti/TiN multilayer ?lms on sapphire substrates and measure the re?ectance and transmittance in the wavelength range from 400 to 2000 nm using a spectrophotometer. The optical constants (complex refractive indices), including the refractive index n and the extinction coef?cient k, have been derived. With the extracted refractive indices, we propose an optical stack structure using low-loss amorphous Si (a-Si) anti-re?ective coating and a backside aluminum (Al) re?ecting mirror, which can in theory achieve 100% photon absorption at 1550 nm. The proposed optical design shows great promise in enhancing the optical ef?ciency of TiN-based microwave kinetic inductance photon-number-resolving detectors.
关键词： TiN,Optical constants,Microwave kinetic inductance detectors,Refractive index
更新于2025-11-14 15:25:21
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Effect of thickness and post deposition annealing temperature on the structural and optical properties of thermally evaporated molybdenum oxide films
摘要： In this paper, the influence of thickness and post deposition annealing temperature on thermally evaporated molybdenum oxide films has been studied. The X-ray diffraction (XRD) and Scanning Electron Microscope (SEM) are used for crystal structural and surface morphological characterization of the films, respectively. The XRD analysis showed that the presence of α-MoO3 and MoO2 crystalline phase of the films annealed at elevated temperature ~ 250 °C after deposition. The optical constants are determined from UV–Vis transmission spectra. The optical band gap and Urbach energy is found to be temperature dependent. The refractive index of the films is estimated by the optical method as well as cross-sectional SEM image analysis. It is found that the refractive index of the films increases from ~ 1.70 to 2.03 with the decrease in film thickness from ~ 2.9 to 1.7 μm. It is also observed that the refractive index decreased from ~ 2.03 to 1.61 with the increase in post deposition annealing temperature from room temperature (RT) to ~ 250 °C. Moreover, extinction coefficient, optical conductivity, porosity, and film density are investigated as a function of source-substrate distance and post deposition annealing temperature. The Photoluminescence (PL) properties of the films are also investigated by recording spectra under the excitation wavelength at 250 nm.
关键词： Optical constants,Molybdenum oxide,X-ray diffraction,Thermal evaporation,Scanning electron microscope
更新于2025-09-23 15:22:29
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Elastic and optoelectronic properties of CaTa2O6 compounds: Cubic and orthorhombic phases
摘要： Using first principles density functional theory (DFT) simulations, the structural, electronic, optical and elastic properties of CaTa2O6 oxide for cubic and orthorhombic phases are studied by highly accurate (FP-LAPW) method within the GGA + U approximation. The calculated lattice parameters are consistent with available experimental data. The electronic band structure calculations have shown that the band gaps in CaTa2O6 are equal to 3.08 eV and 4.40 eV for the cubic and orthorhombic structures, respectively. For both the phases the main optical properties, e.g., absorption coefficient, dielectric constant, energy loss function, and reflectivity, refractive index, and extinction coefficient are calculated and discussed in detail in the spectral range 0-14 eV. Cubic and orthorhombic phases exhibit significantly different optical characteristics. The electronic bonding characters of CaTa2O6 with different symmetries are explored via charge density distribution mapping. Strong covalent bonding character dominates in both the phases of CaTa2O6. Elastic properties of CaTa2O6 for cubic and orthorhombic phases are also investigated. The stress strain method is used for the determination of elastic constants in both the phases. The bulk modulus, shear modulus, Young’s modulus, along with the important elastic anisotropy factors and Poisson’s ratio are studied in detail.
关键词： First principles density functional theory,GGA+U approximation,FP-LAPW method,Optical constants,Electronic band structure,electro technical materials
更新于2025-09-23 15:22:29
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Optical and electrical properties of thermally evaporated Se90Sb10 thin film
摘要： Chalcogenide Se90Sb10 thin ?lms are deposited by thermal evaporation from the bulk alloy. X-ray di?raction examination for the annealed ?lms shows the amorphous-crystalline transformation. This is bene?cial for optical disk data storage technology. The crystallinity is improved by increasing the annealing temperature. The ?lms annealed at relatively low temperatures exhibit highly transparence reaching to about 90% at incident light of wavelength of 900 nm. The as-prepared and annealed Se90Sb10 ?lms reveal an indirect allowed optical transition. The annealed ?lm at 473 K has an optical band gap of 1.676 eV which is suitable value for solar cell as photovoltaic application. Both the indirect optical energy band gap (Eg) and the oscillator energy (Eo) decrease whereas the oscillator strength (Ed) increases with increasing the annealing temperature. The annealing increases the conductivity and decreases the activation energy for conduction resulting in enhancement of ?lm properties for adapting to solar cells.
关键词： Electrical conductivity,Chalcogenide,Optical constants,Thin ?lms
更新于2025-09-23 15:21:21
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Highly transparent zinc nitride thin films by RF magnetron sputtering with enhanced optoelectronic behavior
摘要： Transparent semiconducting nitrides are important materials for many modern technologies. Here, optical transparent semiconducting zinc nitride (Zn3N2) thin films have been developed by reactive RF magnetron sputtering at different nitrogen (N2) contents. The deposited films are found to be cubic with preferred orientation of (3 2 1) plane. High optical transmittance (～96%) and refractive index (1.32) at the wavelength of 500 nm and optical band gap of 3.1 eV have been observed for the films deposited at 45% nitrogen content. The investigation on other optical constants such as extinction coefficient and dielectric constant as a function of wavelength shows enhanced optical behavior. The Zn3N2 thin films show n-type conductivity with carrier concentration of ～1020–1021 cm?3, mobility in the range of 4 to 56 cm2/Vs (which is 1–2 times higher than the values of TCOs) and resistivity around 10?4 Ωcm as a function of nitrogen content. These results suggested that Zn3N2 thin films could perform as potential transparent semiconductors for thin film solar cells.
关键词： Electron mobility,Zinc nitride,Optical constants,Transparent semiconductor,Reactive RF sputtering
更新于2025-09-23 15:21:21
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Temperature Dependence of Phonon Modes, Optical Constants, and Optical Band Gap in Two-Dimensional ReS2 Films
摘要： Effects of temperature on the optical properties of the large area ReS2 films (ten layers), which is prepared by chemical vapor deposition on SiO2/Si substrates, have been investigated by Raman and reflectance spectra. The phonon frequencies of eighteen Raman modes redshift about 3 cm-1 with increasing the temperature from 140 K to 320 K. The optical constants (n and k) at a photon energy region of 0.46-6.52 eV are obtained, and the values blue-shift with increasing temperature. Four interband transitions (Ep1, Ep2, Ep3, and Ep4) are observed at 1.53 eV, 2.98 eV, 4.25 eV, and 5.37 eV at 303 K, and the values increase with increasing the temperature. The physical origins have been assigned to the different band-to-band direct electronic transitions. The optical band gap of the ReS2 films increases from 1.36 eV at 303 K to 1.38 eV at 383 K. Based on the first-principles calculation results, the band gap increases from 1.32 eV at a normal lattice constant to 1.40 eV at 1.1 times lattice constant. This is because the energy levels present the tendencies of degeneracy, which due to the coupling between Re 5d orbital and S 3p orbital is weaker and the energy level splitting is smaller with increasing temperature.
关键词： optical constants,ReS2 films,2D materials,phonon modes,optical band gap
更新于2025-09-23 15:21:01
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DFT study of SmXO <sub/>3</sub> (X = Al and Co) for elastic, mechanical and optical properties
摘要： The first-principles study of cubic perovskites SmXO3 (X=Al and Co) for elastic, mechanical and optical properties is done in the framework of density functional theory (DFT). Optimized structural parameters are obtained first to find mechanical and optical properties of the materials. These obtained structural parameters are in accordance with the published data. The cubic elastic parameters C11, C12 and C44 are then calculated by using generalized gradient approximation (GGA) as an exchange correlation functional in Kohn–Sham equations. Poisson’s ratio, shear modulus, Young’s modulus and anisotropic factor are deduced from these elastic parameters. These compounds are found to be elastically anisotropic and SmAlO3 is brittle while SmCoO3 is ductile. Their covalent nature is also discussed by using Poisson’s ratio. In addition, optical properties like absorption coefficient, extinction coefficient, energy loss function, dielectric function, refractive index, reflectivity and optical conductivity are studied. This study predicts that SmAlO3 and SmCoO3 are suitable for optoelectronic devices.
关键词： mechanical properties,optical properties,perovskites.,elastic constants,DFT,optical constants
更新于2025-09-19 17:15:36
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Structural and Optical Properties of Ga2Se3 Crystals by Spectroscopic Ellipsometry
摘要： Optical and crystalline structure properties of Ga2Se3 crystals were analyzed utilizing ellipsometry and x-ray diffraction (XRD) experiments, respectively. Components of the complex dielectric function (e = e1 + ie2) and refractive index (N = n + ik) of Ga2Se3 crystals were spectrally plotted from ellipsometric measurements conducted from 1.2 eV to 6.2 eV at 300 K. From the analyses of second-energy derivatives of e1 and e2, interband transition energies (critical points) were determined. Absorption coefficient–photon energy dependency allowed us to achieve a band gap energy of 2.02 eV. Wemple and DiDomenico single effective oscillator and Spitzer–Fan models were accomplished and various optical parameters of the crystal were reported in the present work.
关键词： critical points,optical properties,optical constants,Semiconductors
更新于2025-09-19 17:15:36