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The Ag-mixed Se 70 Te 30 thermally deposited semiconducting thin films show interesting thermoelectric properties. As the Ag content in the structure of Se 70 Te 30 increases, the Seebeck coefficient increases. The semiconductive thin films reveal a p-type behavior. The dark conductivity increases at 300 K, whereas a reduction in corresponding activation energy for dark, photo and thermal response is observed with the increase in the Ag content. It is elucidated that the power factor for Se 70 Te 30 100 - x Ag x (0.0 ≤ x ≤ 8.0 at. %) semiconducting thin films can be tuned and enhanced at varied temperature ranges through adjusting the addition amount of Ag. These results indicate that these semiconducting thin films have remarkable potential as thermoelectric generators. [ABSTRACT FROM AUTHOR]

XRD of thermally evaporatedGe0.15Te0.80Cu0.05thin films at higher deposition pressure show amorphous state while the lower deposited films show poly crystalline state. Different preferred orientations were identified; (222), (411) for GeTe4, (101), (003) for Te and (311) for GeTe. The corresponding crystallites sizes are 5,10,11,10 and 9 nm respectively. The lower deposition pressure, LDP develops the optical properties; direct, indirect optical gap and phonon energy are increasing as a function of deposition pressure. Optical gap was affected by carrier concentration. Burstein-Moss effect, B-M effect was used to discuss the variation of the optical properties. [ABSTRACT FROM AUTHOR]

Thermal evaporation technique was used to prepare the Platinum octaethylporphyrin (PtOEP) thin films at room temperature. The deposited films were studied before and after thermal annealing at 373 and 473 K for 3 h under vacuum (10 −3 Pa). The film structure, surface morphologies and molecular structure were investigated as a function of annealing temperature by X-ray Diffraction (XRD), Field-Emission Scanning Electron Microscopy (FESEM) and Fourier-transform infrared techniques (FT-IR) respectively. The results confirmed that the as-deposited and annealed films have nanostructural features. Optical constants of the as-deposited and annealed films have been obtained in the wavelength range 200–1100 nm by using spectrophotometric measurements. Analysis of the spectra of absorption coefficient showed indirect allowed transition and optical energy gap found to decrease with increase in annealing temperature. The dispersion of refractive index at the normal dispersion ( λ > 600 nm) was discussed in terms of single oscillator model of Wemple–Didomenico. Based on generalized Miller’s rule the third order non-linear susceptibility, χ (3) and nonlinear refractive index, n 2 were estimated and studied at lower photon energy and showing lower value for the annealed film. [ABSTRACT FROM AUTHOR]

5,10,15,20-Tetraphenyl-21 H, 23 H-porphyrin nickel(II), NiTPP films were prepared by thermal evaporation method of mother powder material. Electrical as well as thermo-electric properties were investigated for the as-deposited and annealed NiTPP films. The effect of NiTPP film thickness (160-460 nm) and isochronal annealing in temperature range (300-348 K) on DC electrical properties were studied. Both bulk resistivity and the mean free path were determined; their values are 1.38 × 10 Ω cm and 0.433 nm, respectively. The electrical conductivity exhibits intrinsic and extrinsic conduction. The values of activation energy in extrinsic and intrinsic regions are 0.204 and 1.12 eV, respectively. Mott's parameters were determined at low temperature. Seebeck coefficient indicates p-type conduction of NiTPP films. Carrier density, mobility and holes concentration were determined. Seebeck coefficient decreases with the increasing of temperature, while the conductivity increases with the increasing of temperature. The difference between the conductivity and the thermoelectric power activation energies was attributed to the potential barrier grain boundaries. [ABSTRACT FROM AUTHOR]

In the current investigation, homogenous thin films from TeO 2 -boro-bismuthate glasses are synthesized by the thermal evaporation process. The film reflectivity, R (λ) , was measured within the 0.22 − 2.5 μ m spectral range. The complex refractive index (n ˇ = n + i k) and the film thicknesses were estimated with high accuracy. The increment of TeO 2 was found to increase the optical gap (E g) values, whereas the refractive index (n) decreased. The dispersion of n was explained following the Wemple–DiDomenico model. The absorption mechanism in the explored films was found to obey the allowed indirect optical transition rule. The E g compositional dependence is analyzed based on the Tauc's slope B0.5 and the width of the localized states, which decreased with increasing TeO 2 content. The other optical parameters, such as dielectric loss, the plasma frequency, dissipation factor, as well as the optical conductivity of the films, were estimated. [ABSTRACT FROM AUTHOR]

Abstract: X-rays diffraction and scanning electron microscope were used to investigate the structural properties of tetraphenylporphyrin, TPP, which is polycrystalline in a synthesized condition. It turns to amorphous structure upon thermal deposition. Annealing temperature ranging from 295 to 473K does not influence the amorphous structure of films. The optical properties of TPP were investigated using spectrophotometric measurements of the transmittance and reflectance at normal incidence in the wavelength range of 200–2200nm. The absorption spectra were recorded in UV–visible region of spectra for the as-deposited and annealed samples show different absorption bands, namely four bands labeled as Q-band in visible region of spectra and a more intense band termed as the Soret band in near UV region of spectra. The Soret band shows its splitting (Davydov splitting). Two other bands labeled N and M appear in UV region. The film thickness has no influence on optical properties of films while annealing temperatures have a slight influence on optical properties of TPP films. The type of optical transition in as deposited and annealed conditions of films was found to be indirect allowed band-gap. Both fundamental and onset energy gap decreases upon annealing. [Copyright &y& Elsevier]

Abstract: Thin films of 5,10,15,20-Tetraphenyl-21H,23H-porphine-nickel(II) were prepared by thermal evaporation technique onto clean quartz and glass substrates. Thermogravimetric analysis, X-Ray Diffraction, Scanning Electron Microscope, Transmission Electron Microscope and Fourier transforms infrared spectroscopy were used to investigate the structural properties of the as-prepared and annealed 5,10,15,20-Tetraphenyl-21H,23H-porphine-nickel(II) films. Morphology, crystallite size and dislocation density were enhanced by annealing and included within nanometric scale. The crystallite sizes were 98 nm for powder form and 13, 41.4 and 64.7 nm for the annealed films at 373, 473 and 573 K respectively. Fourier transforms infrared spectroscopy studies released that powder, as-prepared and annealed NiTPP films were stoichiometric. The obtained films were characterized by nanostructure property. [Copyright &y& Elsevier]

Abstract: ِAmorphous chalcogenide of As–Se–Tl glassy alloys was prepared by melt quenching technique. Films were deposited on a transparent glass substrate using thermal evaporation technique. The optical characterization of thin As–Se–Tl films was studied by the analysis of transmission spectra, measured at normal incidence, in the spectral range 200–3000. The envelope method, proposed by Swanepoel, is a commonly used method for studying optical properties of films with uniform and non uniform thickness. Thickness values as well as optical constants, refractive index, Dispersion energy, Urbach and static refractive index or infinite wave length dielectric constant, are calculated using Wemple–DiDomenico model near infrared region using the envelopes of the transmittance spectrum of the films. The values of optical constants: absorption coefficient, Urbach tail, refractive index etc. have been determined. Urbach tail is estimated using Tauc''s extrapolation and is found to increase from 0.69 to 0.91eV with the Tl addition. This behavior of Urbach tail is interpreted in terms of Tauc''s Model. Other optical constants are interpreted in terms of Wemple–DiDomenico model, chemical bond approach, electro-negativity difference of the atoms involved and cohesive energy of the system. [Copyright &y& Elsevier]

Abstract: As20Se60Tl20 bulk material was prepared firstly then thermal evaporation method was used to prepare As20Se60Tl20 films. Illumination effect at room temperature for the mentioned films has been studied within the homogeneous glass-forming region. The prepared film samples were amorphous, this is depicted by X-ray chart. Optical properties have been studied using spectrophotometric measurements. The absorption edge was shifted to shorter wavelengths due to light exposure or photobleaching effect. It was found that the extinction coefficient and the optical band gap have opposite character after illumination. [Copyright &y& Elsevier]

Se–Te materials have shown promise in optoelectronic applications. A combination of enhanced optical and mechanical properties represents a good candidate for optical limiting devices. Here, we report the influence of Ag additive on the optical and mechanical properties of (S e 70 T e 30) 100 − x A g x (0.0 ≤ x ≤ 8.0 a t. %) chalcogenide thin films. The reflectance spectra of amorphous thin films have been analyzed in the spectral range 0.3 μm–2.5 μm. The optical parameters are obtained using reflectance spectra of the thin films. The refractive index increases with the addition of Ag , while the optical band gap decreases from 1.40 eV to 1.11 eV. The reduction in the optical band gap is correlated with the raise in the concentration of defect states and the disorder. The nonlinear refractive index and nonlinear susceptibility have been evaluated and found to show an augmented response with Ag content. The value of (χ (3)) increases from 3.44 × 10−11 esu to 7.66 × 10−11 esu and n 2 from 3.98 × 10−10esu to 8.08 × 10−10esu. The mechanical properties have also been analyzed theoretically and ultrasonically with Ag incorporation to SeTe thin films. • Optical and mechanical properties of (S e 70 T e 30) 100 − x A g x (0.0 ≤ x ≤ 8.0 a t. %) are investigated. • Single reflectance spectrum (0.3 μm–2.5 μm) is used to determine optical properties. • Optical band gap decreases from 1.40 eV to 1.17 eV for x = 0 to 8 at.%. • The value of (χ (3)) increases from 3.44 × 10−11 esu to 7.66 × 10−11 esu and n 2 from 3.98 × 10−10esu to 8.08 × 10−10esu. • Bulk modulus has been observed to decrease with increasing Ag content. [ABSTRACT FROM AUTHOR]

Thin amorphous films of Cu x (Ge 3 Se 7) 100-x (0 ≤ x ≤ 12 at. %) were prepared on glass substrates by the thermal evaporation method. The dc electrical resistivity (ρ dc) and current-voltage (I–V) characteristics were measured within the temperature range from 190 to 420 K for the prepared films. For x ≤ 6 at. %, the electrical conductivity (σ dc) shows three temperature regimes arise from three different conduction mechanisms, while for x = 9 and 12 at. %, only two distinct regimes were observed. The Fermi energy (E f) and the charged carriers' mobility (μ o) of the studied thin films were estimated. The variation of current density (J) as a function of electric field (E) indicating Ohmic behavior for low applied electric field (E < 2.4 × 105 V/cm). Above such electric field (at higher voltage V > 12 V), a space charge limited conduction (SCLC) occurs. By fitting the experimental data according to the SCLC, the density of localized states (DOS) close to Fermi level was estimated. The increasing of the DOS with an increase of the Cu content can be ascribed to increasing the defect states. [ABSTRACT FROM AUTHOR]

Rare earth doping increases the emission range and is an attractive candidate for sensing applications because of its good infrared properties. Here (Dy) doped (GeSe 2) 80 (In 2 Se 3) 20 thin films have been deposited via thermal evaporation and then annealed at different temperatures in order to investigate its effect on various parameters. Refractive index, calculated by drawing lower and upper envelopes, has been used to calculate the Wemple DiDomenico and Sellmeier oscillator parameters. The calculation of dielectric parameters shows a decrease in the loss of electromagnetic energy. Optical energy bandgap (E g) values increase from 1.86 eV to 2.10 eV. To a good approximation, E 0 and E g follow Tanaka's relation: E 0 / E g ≈ 2. The electric modulus and complex impedance have been interpreted to give information about the relaxation phenomenon in the films. The calculated nonlinear refractive index values vary from 5.74 × 1011 esu to 3.45 × 1011 esu which are far higher than the silica glasses. • Dy doped (GeSe 2) 80 (In 2 Se 3) 20 thin film is prepared and annealed at different temperatures to examine the optical parameters. • Themo induced effect has shown a change in the optical bandgap from 1.86 eV to 2.10 eV. • Linear and nonlinear optical properties are evaluated. • The static Linear refractive index is noticed to decrease from 2.57 to 2.42 with annealing temperature. • Dispersion energy decreases from 20.94eV to 19.38eV with annealing temperature. [ABSTRACT FROM AUTHOR]

Abstract: Optical properties of the as-deposited and annealed films of 5, 10, 15, 20-Tetraphenyl-21H, 23H-Porphyrin nickel (II), (NiTPP) were investigated using spectrophotometric measurements of both transmittance and reflectance at normal incidence of light in the wavelength range, 200–1100 nm. The obtained data of refractive index, and absorption index, were used to estimate the type of transition and both optical and fundamental gaps. The normal dispersion (λ > 600 nm) of refractive index is discussed in terms of single oscillator model of Wemple-Didomenico, while the anomalous dispersion (λ < 600 nm) is discussed according to multi oscillator. The dispersion parameters; oscillator energy, dispersion energy, optical dielectric constant at higher frequency, lattice dielectric constant, and the ratio of carrier concentration to the effective mass N/m* were determined. The real part of the dielectric constant, the imaginary part of the dielectric constant, the loss factor, the volume and the surface energy loss functions were estimated and discussed. [Copyright &y& Elsevier]

The Co 0.5 Ni 0.5 Ce x Sm y Fe 2-x-y O 4 (CNCSF) XRD pattern revealed the purity of the samples without any secondary phase. The crystallite size CNCSF are in nano range. Further, the calculated lattice parameter of CNCSF are found to increasing with the RE content. From SEM micrographs surface morphology and the microstructure of the CNCSF was studied. The porous nature of the samples is revealed by SEM, which will aid in increasing their sensing response. Energy dispersive X-ray spectroscopy (EDS) patterns have confirmed the stoichiometric presence of Co2+ Ni2+, Ce3+, Sm3+ and Fe3+, those are used to prepare the CNCSF. The dielectric behaviour is similar to that of conventional spinel ferrite structures, in that the dielectric constant is highest at low frequencies and decreases at higher frequencies due to electron hopping, resulting in dielectric dispersion. Only one semicircle is seen in each Cole-Cole plot, which has uncovered that the contribution to conductivity is predominantly from the grain boundaries. At room temperature, the gas sensing responses of CNCSF thin films were investigated. For liquified petroleum gas (LPG), the gas sensing characteristics of the prepared thin films were investigated. At room temperature, the x = 0.03 thin films showed excellent sensitivity to liquified petroleum gas. The sensing response and recovery time of all of the thin films that had been prepared were reported. The sensing response of x = 0.03 thin films was highly stable over a period of 60 days on exposure to LPG (1000 PPM v), according to the stability analysis. The sample thin film with x = 0.03 can be utilized in gas sensor technology, particularly for the detection of LPG at room temperature, due to its increased sensitivity, quick response and recovery times, and stability. Pictorial representation of the material deposited on the gas substrate and gas sensing setup, SEM micrographs, The gas response in x,y = 0.0 to x,y = 0.03 thin film samples on exposure of different concentration of LPG on complete gasification and degasification process. [Display omitted] • LPG gas sensing characteristics of the Co0.5Ni0.5CexSmyFe2-x-yO4 were investigated for the first time. • The sensing response of x = 0.03 sample is stable over a period of 60 days on exposure of LPG (1000 PPMv). • The sample x = 0.03 can be utilized in the detection of LPG at room temperature. • The dielectric constant is highest at low frequencies due to electron hopping. [ABSTRACT FROM AUTHOR]

Abstract: Thin films of As20Se80− x Tl x ; () were prepared by thermal evaporation of the bulk materials. The effect of Tl addition on the electrical properties of As–Se–Tl chalcogenide semiconductors has been studied in the homogeneous glass-forming region through the low- and high-temperature range (173–373K). The results indicated that the conduction in these glasses is through an activated process having two conduction mechanisms (band conduction in extended states and hopping conduction in localized states). The thallium in the As–Se–Tl ternary system tends to decrease the glass transition and melting temperatures and increase the DC conductivity in the amorphous phase. The activation energy for As20Se80− x Tl x is found to vary between 0.9 and 0.64eV. A comparison between computed and measured densities was performed. The measured density appeared to be smaller than the computed one. This difference is attributed to the transformation of the material to the amorphous nature. [Copyright &y& Elsevier]

Abstract: Thermal evaporation technique was used to deposit various samples of As20Se80− x Tl x on a glass substrate where (5⩽x⩽35 at%). The XRD studies were carried out for thin films of As20Se80− x Tl x , where the results confirm the amorphous nature for the as-deposited films. Chemical compositions of thin films analysis were done using EDS. The optical energy gapEgopt of the as-deposited films was determined from transmission and reflection spectra. The decrease ofEgopt , with increasing Tl content was attributed to the effect of localized states. The optical constants n, k could be determined and were found to increase with the increasing of Tl-content. The dielectric constants (ε ∞ and ε L) were increasing with the increasing of Tl-content. Dispersion parameters were determined according to Wemple–DiDomenico relationship. [Copyright &y& Elsevier]

Highly homogenous crystal violet (CV) thin films are grown by spin coating technique. X-ray diffraction (XRD) measurements have been carried out to identify the dominant orientation of the films. The XRD pattern of as-deposited film showed an amorphous structure which turns into nanocrystalline by thermal annealing at 150 °C for 1 h. The spectroscopic characterization of as-deposited and annealed CV films was estimated via spectrophotometric measurements of transmission and reflection in the spectral range 190–2000 nm. Optical constants of CV films were determined. Wemple-DiDomenico model was applied to the normal dispersion region of refractive index spectrum and from which, many dispersion parameters were calculated. The type of most probable transitions and values of optical energy gaps for CV films were estimated by Tauc plot. The dissipation energy and volume & surface loss functions were estimated. The influence of annealing temperature on the spectroscopic properties, dispersion parameters and energy loss functions were investigated which revealed an improvement in the optical properties and decreased values of energy loss functions for the annealed CV films. The obtained results of optical features for CV films reveals that CV films are an excellent potential absorbing material in solar energy conversion and storage devices. [Display omitted] • Thin films of Crystal violet (CV) are grown by spin coating technique. • The XRD patterns of CV thin films have been investigated. • The optical constants of CV thin films have been calculated. • Dispersion parameters of CV films were calculated via single oscillator theory. • Energy loss functions of CV films were evaluated. [ABSTRACT FROM AUTHOR]

We synthesized a novel isatin hydrazone derivative 3-(((E)-3-ethoxy-2-hydroxybenzylidene)hydrazineylidene)indolin-2-one (IL) via condensation of isatin hydrazide with 3-ethoxy-salicylaldehyde in methanol. Then ZnO was chelated with the ligand (IL) to produce a novel ZnOIL complex. The characteristics of the IL and ZnOIL compounds were compared using various techniques, including nuclear magnetic resonance, ultraviolet–visible, infrared, and mass spectroscopy, and elemental analyses to confirm their chemical compositions. The optical properties of the IL and ZnOIL thin films were studied based on spectroscopic measurements of their absorbance, transmittance, and reflectance within the range of 300–2500 nm. The optical constants, dielectric parameters, and dispersion energies were determined and interpreted. The electronic inter-band transitions of the IL and ZnOIL films were characterized by indirect allowed transitions. The value of the optical band gap (E g) was determined as 2.14 eV for the IL film, but chelation of IL with ZnO decreased E g to 2.02 eV. The surface and volume energy loss functions were lower for ZnOIL compared with IL. The structural and the optical features of ZnOIL may be tuned, and thus it is a promising candidate material for applications in energy conversion and storage devices. Image 1 • New isatin hydrazone derivative (IL) and its complex with ZnO (ZnOIL) synthesized. • Characteristics of IL and ZnOIL analyzed. • Optical constants and dispersion parameters determined for IL and ZnOIL films. • Surface and volume energy loss functions investigated for IL and ZnOIL films. [ABSTRACT FROM AUTHOR]