The photoconductivity and its dependence on light intensity have been investigated in a-Ge20Se80 thin films as a function of temperature between (293–323)K. The result showed that the photoconductivity and photosensitivity increase with increase of annealing temperature. This behavior is interpreted in terms of the dispersive diffusion –controlled recombination of localized electrons and holes.
The effect of heat treatment on the optical properties of the bulk heterojunction blend nickel (II) phthalocyanine tetrasulfonic acid tetrasodium salt and Tris (8-hydroxyquinolinato) Aluminum (NiPcTs/Alq3) thin films which prepared by spin coating was described in this study. The films coated on a glass substrate with speed of 1500 rpm for 1.5 min and treated with different annealing temperature (373, 423 and 473) K. The samples characterized using UV-Vis, X ray diffraction and Fourier transform Infrared (FTIR) spectra, XRD patterns indicated the presence of amorphous and polycrystalline blend (NiPcTs/Alq3). The results of UV visible shows that the band gap increase with increasing the annealing temperature up to 373 K and decreases with
... Show MoreGenerally the a.c. conductivity shows a power law in frequency s () where the exponent s ≤ 1. As the frequency goes to zero the conductivity become frequency independent. The a.c. conductivity was studied for the Ge1-xSex thin films to see how the selenium contents affect the permittivity and the permeability for the Ge1-x Sex. The thin films prepared by thermal evaporation at room temperature and under vacuum (~2 x10-5toor) using Edward coating unit model 306A. From the relation between ln conductivity and ln w, the effect of selenium contents in Ge1-x Sex thin films on the exponent value, the relaxation time and the maximum barrier height. An algebric fitting method for circles and circular arcs was used to find the permit
... Show More(Sb2S3)1-xSnx thin films with different concentrations (0, 0.05 and
0.15) and thicknesses (300,500 and 700nm) have been deposited by
single source vacuum thermal evaporation onto glass substrates at
ambient temperature to study the effect of tin content, thickness and
on its structural morphology, and electrical properties. AFM study
revealed that microstructure parameters such as crystallite size, and
roughness found to depend upon deposition conditions. The DC
conductivity of the vacuum evaporated (Sb2S3)1-x Snx thin films was
measured in the temperature range (293-473)K and was found to
increase on order of magnitude with
Spin coating technique used to prepare ZnPc, CdS and ZnPc/CdS blend thin films, these films annealed at 423K for 1h, 2h and 3h. Optical behavior of these films were examined using UV-Vis. and PL. The absorption spectrum of ZnPc shows a decreasing in absorption with the increase of annealing time while CdS spectrum give a clearly absorption peak at~510 nm. Energy gap of ZnPc increases from 1.41 to 1.52 eV by increasing the annealing time. Eg of CdS decrease by increasing annealing time, from 2.3 eV to 2.2 eV. The intensities of the peaks obtained from PL spectra were strongly dependent on annealing time and confirmed the results obtained from UV-Vis. D.C. conductivity measurement showed that all the thin films have two differen
... Show Morein this paper, the current work was devoted to the manufacture of TiO2 nanoparticles doped with manganese, synthesis by the sol-gel technique using a dip-conting device, for their hydrophilic properties and photocatalytic activity, and the products were characterized by X-ray diffraction, scanning electron microscopy, and Uv-Visible absorption, and the results XRD showed an phase Anatase , and the results of the SEM Explained the shape of the morphology of the samples after the doping process compared with pure TiO2, and the results of a shift in light absorption from ultraviolet rays to visible light were evident. The results showed that the thin films have a high wettability under visible rays
... Show MoreZinc Oxide (ZnO) is considered as one of the best materials already used as a window layer in solar cells due to its antireflective capability. The ZnO/MgF2 bilayer thin film is more efficient as antireflective coating. In this work, ZnO and ZnO/MgF2 thin films were deposited on glass substrate using pulsed laser deposition and thermal evaporation deposition methods. The optical measurements indicated that ZnO thin layer has an energy gap of (3.02 eV) while ZnO/MgF2 bilayer gives rise to an increase in the energy gap. ZnO/MgF2 bilayer shows a high energy gap (3.77 eV) with low reflectance (1.1-10 %) and refractive index (1.9) leading to high transmittance, this bilayer could be a good candidate optical material to improve the performance
... Show MoreSilver sulfide and the thin films Ag2Se0.8Te0.2 and Ag2Se0.8S0.2 created by the thermal evaporation process on glass with a thickness of 350 nm were examined for their structural and optical properties. These films were made at a temperature of 300 K. According to the X-ray diffraction investigation, the films are polycrystalline and have an initial orthorhombic phase. Using X-ray diffraction research, the crystallization orientations of Ag2Se and Ag2Se0.8Te0.2 & Ag2Se0.8S0.2 (23.304, 49.91) were discovered (XRD). As (Ag2Se and Ag2Se0.8Te0.2 & Ag2Se0.8S0.2) absorption coefficient fell from (470-774) nm, the optical band gap increased (2.15 & 2 & 2.25eV). For instance, the characteristics of thin films made of Ag2Se0.8Te0.2 and Ag2Se0.8S0.2
... Show MoreIn this study, tin oxide (SnO2) and mixed with cadmium oxide (CdO) with concentration ratio of (5, 10, 15, 20)% films were deposited by spray pyrolysis technique onto glass substrates at 300ºC temperature. The structure of the SnO2:CdO mixed films have polycrystalline structure with (110) and (101) preferential orientations. Atomic force microscopy (AFM) show the films are displayed granular structure. It was found that the grain size increases with increasing of mixed concentration ratio. The transmittance in visible and NIR region was estimated for SnO2:CdO mixed films. Direct optical band gap was estimated for SnO2 and SnO2 mixed CdO and show a decrease in the energy gap with increasing mixing ratio. From Hall measurement, it was fou
... Show MoreTiO2 thin films were deposited by reactive d.c magnetron sputtering method on a glass substrate with various ratio of gas flow (Oxygen /Argon) (50/50, 100/50 and 150/50) at substrate temperature 573K. It can be observe that the optical energy gap of TiO2 thin films dependent on the ratio of gas flow (oxygen/argon), it varies between (3.45eV-3.57eV) also it is seen that the optical constants (α, n, K, εr and εi ) has been varied with the change of the ratio of gas flow (Oxygen /Argon).