Preparation of cadmium oxide films by spray pyrolysis and its conversion into cadmium chalcogenide films (original) (raw)
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Studies on nanocrystalline cadmium sulphide (CdS) thin films deposited by spray pyrolysis
Solid State Sciences, 2010
Cadmium chalcogenides with appropriate band gap energy have been attracting a great deal of attention because of their potential applications in optoelectronic devices. CdS in the form of thin film is prepared at different substrate temperatures by a simple and inexpensive chemical spray pyrolysis technique. The as-deposited thin films have been characterized by XRD, SEM, EDAX and electrical resistivity measurement techniques. The XRD patterns show that the films are polycrystalline with hexagonal crystal structure irrespective of substrate temperature. SEM studies reveal that the grains are uniform with uneven spherically shaped, distributed over the entire surface of the substrates. Compositional analysis reveals that the material formed is stoichiometric at the optimized substrate temperature. The optical band gap energy is found to be 2.44 eV with direct allowed band-to-band transition for film deposited at 300 C. The electrical resistivity measurement shows that the films are semiconducting with a minimum resistivity for film deposited at 300 C. The thermoelectric power measurement shows that films exhibit n-type of conductivity.
2014
Cadmium oxide (CdO:2%In) thin films have been deposited onto glass substrates from different molar concentration of cadmium acetate precursor solution using a simple spray pyrolysis technique. The structural and optical properties of the films have been characterized by X-ray diffraction study and UV spectroscopy. The crystal structure of the deposited films were found to be polycrystalline of cubic structure with preferentially orientated along (111) crystallographic directions. Increase of molar concentration increases the films packing density and reorient the crystallites along (1 1 1) plane. There is an ancease in the optical transmissions for all films with increasing in the wavelength and molar concentration . For different molar concentrations (0.1M ,0.2 M, and 0.3M), the direct band gap is found to be in the range( 2.3 ,2.35,and 2.45 eV) . The band gap energies depend on molar concentration of solution.
Synthesis and Properties of Cadmium Oxide Thin Films: A Review
2016
Cadmium oxide thin films are important materials for applications in various photoelectric, solar cell, optoelectronic and other kinds on devices. There are several physical or chemical synthetic methods have been used to prepare transparent CdO films as described by many researchers. The X-ray diffraction study has confirmed the formation of CdO with nano-size scale. CdO films are n-type semiconductors and possess a direct band gap of 2.25 to 2.72eV as shown in optical property studies.
Optical and electrical properties of CdO thin films deposited by spray pyrolysis method
Journal of Bangladesh Academy of Sciences
Cadmium oxide (CdO) thin films have been deposited by a locally developed spray pyrolysis method onto glass substrate at 473K. The optical and electrical properties of the as-deposited and annealed films are studied in details. The surface morphology of the samples was studied by scanning electron microscopy (SEM). The SEM micrograph of as-deposited film shows uniform deposition over the substrate well. The optical absorption coefficient (α) of the CdO films was determined from transmittance spectra in the range of wavelength 450-650nm. For different thicknesses (130nm ~ 380nm) of as-deposited films, the direct band gap is found in the range of 2.40 ~2.51 eV and indirect band gap in the range of 1.97 ~ 2.20 eV. Resistivity (ρ) of CdO thin film was measured in the temperature range of 303 to 553K. The resistivity of the films of different thickness initially increases with increase in temperature and reaches a maximum at 430K and then decreases with further increase of temperature. The resistivity of the film exhibits metallic behaviour up to 430 K and above that the film behaves like a semiconductor. Activation energy (∆E) in the semiconductor region is found in the range from 0.049 to 0.075 eV for films of thickness ranging from 160-285 nm.
Optical Properties of Cadmium Oxide (CdO) Thin Films
Cadmium (Cd) is a soft, silver-white or blue lustrous metal typically found in mineral deposits with lead, zinc and copper. Cadmium Oxide thin films have been prepared on a glass substrate at 350 0 C temperature by implementing the Spray Pyrolysis method. The direct and indirect band gap energies are determined using spectral data. The direct and indirect band gap energies decrease with the increasing film thickness. It is noted that for the same film thickness the direct band gap energy is greater than indirect band gap energy. The transmittance increases with the increasing wavelength for annealed and deposited films. It is also noted that for the same wavelength the transmittance for deposited films is greater than the transmittance for annealed films.
Optical and Electrical Characteristics of CdO thin films deposited by Spray Pyrolysis Method
Journal of Bangladesh Academy of Sciences, 2009
Cadmium oxide (CdO) thin films have been deposited by a locally developed spray pyrolysis method onto glass substrate at 473K. The optical and electrical properties of the as-deposited and annealed films are studied in details. The surface morphology of the samples was studied by scanning electron microscopy (SEM). The SEM micrograph of as-deposited film shows uniform deposition over the substrate well. The optical absorption coefficient (α) of the CdO films was determined from transmittance spectra in the range of wavelength 450 - 650nm. For different thicknesses (130nm ~ 380nm) of as-deposited films, the direct band gap is found in the range of 2.40 ~2.51 eV and indirect band gap in the range of 1.97 ~ 2.20 eV. Resistivity (Ï) of CdO thin film was measured in the temperature range of 303 to 553K. The resistivity of the films of different thickness initially increases with increase in temperature and reaches a maximum at 430K and then decreases with further increase of temperatur...
Studies on cadmium oxide sprayed thin films deposited through non-aqueous medium
Materials Chemistry and Physics, 2004
In the present investigation thin films of cadmium oxide (CdO) have been deposited onto the glass substrates by spray pyrolysis technique using 0.2 M non-aqueous solution of the cadmium acetate. Cadmium acetate has been used as a precursor due to its relatively lower decomposition temperature. The films were deposited by using air as a carrier gas with the spray rate of 6 ml min −1. The films were deposited onto the ultrasonically cleaned glass substrates at different substrate temperatures ranging from 573 to 773 K at the step of 25 K. The X-ray diffraction (XRD) studies show that the films are polycrystalline with preferred orientation along (1 1 1) plane. It is further revealed that the films deposited at 623 K show better crystallinity as compared to the films deposited at lower and higher substrate temperatures. The dc electrical resistivity measurement was carried out in the temperature range 300-500 K and it is found that films prepared at 623 K substrate temperature exhibit lower resistivity which is complementary to XRD results. Optical absorption studies of the films have been carried out in the wavelength range 350-850 nm and the data were analyzed to determine the band gap energy of the deposited material. The band gap energy is estimated to be 2.31 eV. These results are in good agreement with those reported earlier by others.
Journal of Materials Research and Technology, 2013
In this research, pure and copper doped cadmium oxide thin films were prepared by Successive Ionic Layer Adsorption and reaction (SILAR) method using cadmium acetate as the Cd source (cation) and hydrogen peroxide (anion). Optical transmittance is measured by UV-visible spectrophotometer, it is revealed that the copper doping and annealing at 300 • C improves the transmittance of these films. The optical band gap of CdO increased to (2.8 eV) with Cu doping, but it is decreased to (2.4 eV) with annealing. The results show that the pure and doped CdO thin films at annealing temperature of 300 • C have grain size in the range of 19.1 nm and 44.4 nm, respectively.
Cadmium Sulphide is an n-type semiconductor and it is perfectly suitable for a window layer in thin films based solar cells due to its desirable structural and optical properties. CdS thin films have been coated on microscopic glasssubstrate around 300⁰ C by spray pyrolysis technique. Cadmium acetate and Thiourea in different concentrations were used as precursors. The fabricated films are characterized for various properties. Their structural properties were studied by X-ray diffraction,morphological properties are studied by SEM with EDX, and optical studies determined by UV-VIS spectrometry. The band gap value of the CdS thin films varied from 2.1eV to 2.4eV.
Impact of zinc incorporation on structural and some optical properties of cadmium oxide thin films
PROCEEDINGS OF THE III INTERNATIONAL CONFERENCE ON ADVANCED TECHNOLOGIES IN MATERIALS SCIENCE, MECHANICAL AND AUTOMATION ENGINEERING: MIP: Engineering-III – 2021
In this work, ZnCdO thin films were prepared by using Spray pyrolysis technique. The impact of Zn dopant concentrations on the morphological, structural and optical properties have been presented using scanning electron microscopy (SEM) and X-ray diffraction (XRD) and UV-Vis spectrophotometer respectively. SEM analysis illustrates the formation of ZnCdO films have a homogenous and semi uniform structure. The structural results show that the films are polycrystalline. The absorption spectra of the films have high absorbance in the ultraviolet region, with the energy gap was found increasing with increase Zn concentration.