Substrate temperature effect on the structural anisotropy in amorphous Tb–Fe films (original) (raw)
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Journal of physics, 2008
The ZnSe, a wide band gap semiconductor has high potential for application in optoelectronic applications. The structural parameters of a thin film semiconductor largely depend on the preparation method and condition. Transparent ZnSe thin films of thicknesses from 2000 Å to 4500 Å have been prepared by thermal evaporation method on chemically cleaned glass substrates at different substrate temperatures from 300K to 573K. The film structure was studied by X-ray diffraction technique and different micro structural parameters were determined from it. The ZnSe films prepared at higher substrate temperature have been polycrystalline in nature and have a cubic (zinc-blende) structure. The average grain size and average internal strain of these films were calculated from the broadening of the XRD line spectra by plotting Williamson and Hall plots. The grain size of the polycrystalline ZnSe film was found to increase from 160 Å to 454 Å with increase of substrate temperature from 373K to 573K. The internal strain and dislocation density of these films were found to decrease with increase of substrate temperature and also with thickness.
AIMS materials science, 2017
Zinc-selenide thin film was prepared on a soda-lime glass substrate by thermal vapor deposition technique. The X-ray diffraction data confirmed the cubic zincblende structure with a preferred orientation along (111) plane. Different models such as Debye-Scherrer, Size-Strain plot, Williamson-Hall, uniform stress deformation model and uniform deformation energy density model and the so called approximation model were adopted to analyse the XRD data. Detailed microstructural parameters such as crystallite size, strain, stress, isotropic energy density, dislocation denstiy were reported and discussed in comparison with scanning electron microscopy data. The transmission spectra was obtained by UV-Vis-NIR spectrometer in the range of 250-2500 nm at room temperature. Important optical constantssuch as refractive index and dielectric constant was estimated using Swanepoel's envelope method. The same method was used to check the thin film thickness which was found to be 374.9 nm and this thickness was further confirmed by Scanning Electron Microscopy (368.3 ± 19.1 nm). The optical band gap was estimated to be 2.64 eV. The dispersion of refractive index was discussed interms of empirical Cauchy dispersion relation and the dispersion was further analysed by Wemple-DiDomenico Single oscillator model which provide physically meaningful parameters such as static refractive index, oscillator energy and dispersion energy. Both the structural and optical data not only complemented each other but also implied that good quality Zinc-selenide thin film could be deposited on ordinary glass substrates.
STRUCTURAL AND OPTICAL CHARACTERIZATION OF VACUUM EVAPORATED ZINC SELENIDE THIN FILMS
Abstract Optical and structural characterization of Zinc Selenide (ZnSe) thin films thickness ranging between 200 - 500 nm) prepared by vacuum (~10-6 Torr) evaporation method were investigated. The thin films were deposited with varying substrate temperature in the range 373 - 573K. Optical measurements were carried out with UV-VIS-NIR spectrophotometer with photon wavelength ranging between 300-2500 nm. The absorption coefficient, energy band gap, refractive index and extinction coefficient were determined using transmission and reflection spectra at the same wavelength range. The dependence of absorption coefficient in the photon energy had been determined. Analysis showed that direct transition occured with band gap energies ranges from 2.6 eV to 2.9 eV. Refractive indices and extinction coefficients were evaluated in the above spectral range. For structural properties, 300nm films were deposited with varying substrate temperatures and were vacuum annealed in situ at 373 K for one hour. The X- ray diffraction (XRD) patterns showed polycrystalline nature of films having cubic (Zinc blende) structure. The most preferential orientation is along [111] direction for all deposited films together with other abundant planes [220] and [311]. Structural parameters such as lattice constant, grain size, internal stress, microstrain, dislocation density were calculated. The value of lattice constant was estimated to be5.660 Å to 5.761 Å.. The grain sizes were calculated to be which ranges between 266 Å to 384 Å. With the increase of substrate temperature the average grain size of the ZnSe films increases, as revealed from the XRD studies.
Influence of Thickness on the Structural and Optical Properties of ZnSe Thin Films
2010
In this work we report the influence of thickness on the structural and optical properties of Zinc Selenide (ZnSe) thin films prepared in vacuum onto chemically and ultrasonically cleaned glass substrates by using thermal evaporation method. The thickness was varied from 300 to 1000 nm keeping the substrate temperature fixed at 200°C. The film thickness was measured insitu by a quartz crystal thickness monitor. The structural properties of the films were ascertained by X-ray diffraction (XRD) method utilizing a diffractometer. The optical properties were measured in the photon wavelength ranging between 300 to 2500 nm by using a UV-VIS-NIR spectrophotometer. The XRD patterns reveal that the films were polycrystalline in nature exhibiting fcc zincblende structure with average lattice parameter, a = 5.665A. The grain size, strain and dislocation densities of the films have been calculated. The optical transmittance and reflectance were utilized to compute the absorption coefficient, b...
Optical Properties of Polycrystalline Zinc Selenide Thin Films
Materials Sciences and Applications, 2012
Thin films of ZnSe have been deposited onto glass substrates at 373 K by thermal evaporation technique. The X-ray diffractogram confirmed that ZnSe has cubic type crystal structure. The lattice parameters of thin films are almost matching with the JCPDS 5-552 data for Zinc Selenide. The transmittance and reflectance have been measured at normal and near normal incidence, respectively, in the spectral range 200-2500 nm. The dependence of absorption coefficient, α in the photon energy have been determined. Analysis of the result showed that films of different thicknesses, direct transition occurs with band gap energies ranges from 2.2 to 2.6 eV. Refractive indices and extinction coefficients have been evaluated in the above spectral range.
Microstructural characterization and optical properties of ZnSe thin films
Journal of Non-Crystalline Solids, 2006
Zinc Selenide (ZnSe) thin films (d = 0.09-1.25 lm) on glass substrates were prepared by physical vapour deposition under vacuum, using the quasi-closed volume technique. X-ray diffraction (XRD) analysis indicated that the samples are polycrystalline, have a cubic (zinc blende) structure and that the crystallites are preferentially oriented with the (1 1 1) planes parallel to the substrates. The microstructure of ZnSe films examined by transmission electron microscopy (TEM), including electron diffraction (ED) and high-resolution electron microscopy (HRTEM), confirms the preferential orientation of crystallites. The HRTEM micrographs show that preferred orientation of crystallites, along (1 1 1) planes, increases if, after deposition, the samples are subjected to a heat treatment. The spectral dependences of the transmission and absorption coefficients were studied in the range 300-1400 nm. The values of the bandgap energy, E g , calculated from the absorption spectra, ranged between 2.50 eV and 2.80 eV.
IJERT-Study of Physical Characteristics of Zinc Selenide Thin Film
International Journal of Engineering Research and Technology (IJERT), 2015
https://www.ijert.org/study-of-physical-characteristics-of-zinc-selenide-thin-film https://www.ijert.org/research/study-of-physical-characteristics-of-zinc-selenide-thin-film-IJERTV4IS051123.pdf Zinc Selenide (ZnSe) film has been grown on well cleaned glass substrate by thermal evaporation technique under vacuum (5 x 10-6 mbar). The physical characteristics of ZnSe film such as compositional, structural and optical properties were examined using energy dispersive X-ray analysis (EDAX), X-ray diffractometer and UV-Visible spectrophotometer respectively. The EDAX study shows that the ZnSe film is almost stoichiometric. Polycrystalline nature of the film was observed from XRD analysis. It is revealed that deposited film has zinc blende system along with some amorphous phase present in ZnSe film and a preferred (3 1 1) orientation. The grain size and lattice strain have been calculated by Williamson-Hall (W-H) plot.Other relevant structural parameters (dislocation density and internal stress) have been calculated. The value of corrected lattice parameter has been determined using Nelson-Riley error function. The optical parameters (optical band gap, Urbach energy and extinction coefficient) have been found for the wavelength region (300 nm-1100 nm) by absorption spectra.
Effect of thickness on characteristics of ZnSe thin film synthesized by vacuum thermal evaporation
Journal of Theoretical and Applied Physics, 2020
Zinc selenide (ZnSe) thin films with various thicknesses were grown on ultrasonically clean glass substrates using vacuum evaporation of 99.99% pure ZnSe powder. Thickness dependence of the structural, optical and electrical properties was thoroughly investigated. X-ray diffraction (XRD) analyses revealed that (110) ZnSe plane is the dominant crystal plane for all the fabricated films. Both dislocation density and micro-strain go down with the increase in film thickness, indicating lower lattice defects and improvement in crystallinity at higher film thickness. Transmittance spectra show that all the films have almost linear upward tendency of transmittance in near-infrared region and small fluctuations in visible region for higherthickness films. With the increase in film thickness, the optical bandgap increases and also an increasing tendency of dielectric constant was observed. Studies of electrical properties showed a sharp increase in carrier mobility and concentration with film thickness. As the film thickness increases from 30 to 90 nm, the carrier mobility goes up from 255 to 1250 cm 2 /VS and the carrier concentration increases from 2.14 × 10 18 to 9.37 × 10 18 cm −3. The electrical transport properties of the deposited thin films were explained in terms of scattering of the charge carrier.
STRUCTURAL AND OPTICAL CHARACTERIZATION OF VACUUM EVAPORATED ZINC SELENIDE THIN FILMS Andalipa Islam
2016
Optical and structural characterization of Zinc Selenide (ZnSe) thin films (thickness ranging between 200- 500 nm) prepared by vacuum (~10-6 Torr) evaporation method were investigated. The thin films were deposited with varying substrate temperature in the range 373- 573K. Optical measurements were carried out with UV-VIS-NIR spectrophotometer with photon wavelength ranging between 300-2500 nm. The absorption coefficient, energy band gap, refractive index and extinction coefficient were determined using transmission and reflection spectra at the same wavelength range. The dependence of absorption coefficient in the photon energy had been determined. Analysis showed that direct transition occured with band gap energies ranges from 2.6 eV to 2.9 eV. Refractive indices and extinction coefficients were evaluated in the above spectral range. For structural properties, 300nm films were deposited with varying substrate temperatures and were vacuum annealed in situ at 373 K for one hour. Th...