Properties Of CdO Thin Films Research Articles

Annealing Temperature Effects on the Optical Properties of CdO Thin Films Deposited by CSP Technique

By chemical spray pyrolysis method. The CdO thin film prepared at constant film thickness (350 nm). The prepared films are annealed at a temperature of 450 and 500 °C. The optical properties are calculated from the measurement of UV-Visible spectrophotometer spectrum in the range of (300-900) nm at room temperature. The transmittance, absorption coefficient, extinction coefficient, refractive index, and skin depth are calculated as annealing temperature. The energy gap decreased from 2.52 eV to 2.47 eV when the annealing temperature increased from room temperature to 500 °C.

Influence of substrate temperature on ethanol sensing properties of CdO thin films prepared by facile spray pyrolysis method

Transparent conducting CdO thin films were deposited on to glass substrates by spray pyrolysis technique. The depositions were carried out at different substrate temperatures with varying film thickness. The effects of substrate temperature on structural, optical and electrical properties of CdO thin films were systematically studied. The CdO films were polycrystalline in nature with cubic crystal structure showing preferential orientation along (111) direction. Wettability results confirmed that the hydrophobic character of CdO thin film is enhanced with increase in substrate temperatures. The average transmittance is about 80 %, thus the films are transparent in the visible region. The optical band gap value of the CdO films increased from 2.24 to 2.34 eV with increase in the substrate temperature from 200 to 350 °C. Surface morphology studies reveal that the grain size and roughness of the films are increased with increase in the substrate temperature. The minimum value of electrical resistivity of the films is 1.40 × 10−3 Ω cm obtained at 350 °C. The maximum ethanol sensitivity of 33.45 % is observed for the substrate temperature of 300 °C. Thus the results authenticate that the substrate temperature influences the structural, optical, electrical and sensing properties of the deposited films.

Effect of sputtering power on the methane sensing properties of nanostructured cadmium oxide films

Effect of sputtering power on properties of CdO thin film deposited on glass substrate at room temperature by reactive dc magnetron sputtering has been studied. Correlation between the crystal structure, morphological and optical properties were systematically investigated. It has been found that sputtering power increases the crystallographic orientation of the film and at highest sputtering power, deterioration in crystallite growth occurs due to the excessively energetic sputtered particles. The microstructure of the films changes from nano flakes to self-assembled nano-pillar like structure with increasing sputtering power. All the films were highly transparent. The resistivity of the film decreased with increasing sputtering power and at 50W, it increased to 16×10−2Ωcm due to higher ion bombardment effects. The methane sensing properties has been demonstrated with the fabricated CdO based sensor at a relatively low operating temperature.

The synthesis and characterization of sol–gel spin coated CdO thin films: As a function of solution molarity

CdO thin films were deposited by sol–gel spin coating. The structural, morphological and optical characterizations of CdO films were performed as a function of solution molarity. The structural and morphological analyses showed that the films had a polycrystalline cubic structure and the surfaces of films consisted of nano-sized particles. The band gap values were found to be 2.74eV, 2.67eV, 2.62eV, 2.59eV and 2.17eV for 0.05M, 0.1M, 0.3M, 0.5M and 0.7M CdO films, respectively. This study indicates that the properties of CdO thin films could be changed with solution molarity and these films can be used in many technological applications.

Effect of Substrate Temperature on Structural and Optical Properties of CdO Thin Films

Thin films of CdO have been prepared by spray pyrolysis technique. XRD analysis reveals that all the prepared samples were polycrystalline and have preferred orientation along [111] orientation. The surface topography was determined by AFM which indicate that surface roughness and rms roughness were increased by the increasing of substrate temperature. The optical energy gap were determined and its value lies between (2.4-2.5) eV.

Effect of Substrate Temperature on Structural and Optical Properties of CdO Thin Films

Thin films of CdO have been prepared by spray pyrolysis technique. XRD analysis reveals that all the prepared samples were polycrystalline and have preferred orientation along [111] orientation. The surface topography was determined by AFM which indicate that surface roughness and rms roughness were increased by the increasing of substrate temperature. The optical energy gap were determined and its value lies between (2.4-2.5) eV.

This forthcoming publication has been cancelled - The influence of CdS quantum dots incorporation on the properties of CdO thin films

This forthcoming publication has been cancelled - The influence of CdS quantum dots incorporation on the properties of CdO thin films

Optical and Structural Properties of Cdo Thin Film

Optical and Structural Properties of Cdo Thin Film

Study the Effect of Annealing Temperature on Some Physical properties of CdO Thin Film Using a Gas Sensor for CO and H2

Study the Effect of Annealing Temperature on Some Physical properties of CdO Thin Film Using a Gas Sensor for CO and H2

Physical Properties of Cdo Thin Films Prepared by Spray Pyrolysis Technique

Physical Properties of Cdo Thin Films Prepared by Spray Pyrolysis Technique

Some Optical Properties of CdO Thin Films

In this research, thin films of CdO of thicknesses 500nm;450nm;400nm;350nm;300nm±30 have been prepared using chemical spray method. The films have been deposited on Crown glass substrates. Optical studies show that in these films the electronic transition is of the direct transition type. The optical energy gap for the films of as deposited are within the range 2-2.08eV and for those heat treated for an hour at different temperatures: (as deposited 300K; 523K; 548K; 573K) is estimated to be in the range 2.08- 2.85eV. Results analysis exhibits the dependence of optical energy gap on the temperature of heat treatment and the dependence on films thickness was not significant.

OBTAINING AND ELECTRICAL PROPERTIES OF n-CdO/p-Si HETEROJUNCTIONS

There have been investigated the obtaining and structural and optical properties of CdO thin films. Thin films were received with cadmium target by DC method on direct current. From the experimental results there were determined refractive index, extinction coefficient and absorption coefficient. Heterojunction of n-CdO/p-Si has been obtained by sputtering of cadmium oxide on p-Si substrate. Current-voltage characteristics (CV) and capacitance-voltage characteristics have been studied and on their base the main mechanisms of current transport of the formed diode heterojunctions have been evaluated.

Influence of Deposition Time on the Microstructure and Transport Properties of CdO Thin Films Prepared by Chemical Bath Deposition

Transparent thin films of CdO has been deposited on to glass substrates employing chemical bath deposition. The prepared films are reproducible, adherent to the substrate, pinhole free and uniform. Amongst the different process parameters, the deposition time plays a significant role in obtaining device quality transparent CdO thin films. X-ray powder diffraction (XRD) studies indicated that the thin films are polycrystalline in nature with cubic phase with a cell constant of a = 4.638 ?. The surface morphology of the prepared CdO thin films was examined by scanning electron microscopy. The films deposited at 24 hrs exhibited highest optical transmittivity (>80%) and the direct band gap energy was found to vary from 2.50 to 2.91 eV with a rise deposition time from 6 to 30 hrs. The electrical resitivity variations of these films were measured in the temperature range between 30?C and 150?C by four-probe technique.

UV irradiation influence on the structural and optical properties of CdO thin films

Polycrystalline Cd thin films were evaporated in a vacuum onto glass substrates at Cd source temperature of 770 K. The as-deposited Cd films were subjected to a gradual heating at the rate of 5 K/min, up to a temperature of 650 K and were then maintained at this temperature for 5 min. Then, the respective samples were cooled down to room temperature at the same rate. The obtained CdO thin films were UV irradiated for 2 h (150 W mercury lamp, 3.18–3.65 eV). By means of XRD, AFM and XPS techniques, the structural characteristics of the typical obtained CdO samples before and after UV treatment were investigated. The obtained results indicate that the UV treatment induces a recrystallization process: changes in sample morphology, surface roughness and crystallite size and orientation. XRD and XPS studies evidenced an improvement in crystalline structure and stoichiometry. UV irradiated sample shows photo-catalytic properties.

Optical properties of CdO thin films

Cadmium Oxide thin films were deposited on glass substrate by spray pyrolysis technique at different temperatures (300,350,400, 500)oC. The optical properties of the films were studied in this work. The optical band-gap was determined from absorption spectra, it was found that the optical band-gap was within the range of (2.5-2.56)eV also width of localized states and another optical properties.

Influence of dysprosium doping on the electrical and optical properties of CdO thin films

Lightly Dy-doped CdO thin films (molar 0.5%, 1%, 2%, and 2.5%) have been prepared by a vacuum evaporation method on glass and Si wafer substrates. The prepared films were characterised by X-ray fluorescence, X-ray diffraction, UV–vis-NIR absorption spectroscopy, and dc-electrical measurements. Experimental data indicate that Dy 3+ doping slightly stretchy-stresses the CdO crystalline structure and changes the optical and electrical properties. The bandgap of CdO was suddenly narrowed by about 20% due to a little doping with Dy 3+ ions. Then, as the Dy doping level was increased, the energygap was also increased. This variation was explained by the effect of Burstein–Moss energy shift (or bandgap widening effect) together with a bandgap shrinkage effect. The electrical behaviour of the samples shows that they are degenerate semiconductors. However, the 2% Dy-doped CdO sample shows an increase in its mobility by about 3.5 times, conductivity by 35 times, and carrier concentration by 10 times relative to undoped CdO film. From transparent conducting oxide point of view, Dy is sufficiently effective for CdO doping.

Effect of thallium doping on the electrical and optical properties of CdO thin films

AbstractA series of lightly Tl‐doped CdO thin films (1%, 1.5%, 2%, 2.5%, and 3%) have been prepared by a vacuum evaporation method on glass and Si wafer substrates. The prepared films were subjected to structural study by X‐ray diffraction, optical characterisation by UV–VIS–NIR absorption spectroscopy, and dc‐electrical measurements. Experimental data indicate that Tl3+ doping slightly stretching stresses the CdO crystalline structure and changes the optical and electrical properties. It was observed that Tl doping widens the energy gap of CdO from 2.22 eV to 2.83 eV via a Burstein–Moss energy level shift. The band gap shrinkage was also observed for carrier concentrations Nel > 1.13 × 1020 cm–3, which was explained by merging of the impurity band with the conduction band. The optical properties were explained by using Hamberg et al.'s band‐to‐band transitions and classical Drude theory. The electrical behaviour of the samples shows that they are degenerate semiconductors. The 2% Tl‐doped CdO sample shows an increase in its mobility by about 1.4 times, conductivity by 5 times, and carrier concentration by 3.6 times relative to the undoped CdO film. From the transparent‐conducting‐oxide point of view, Tl is sufficiently effective for CdO doping but does not emulate other dopants like In, Sn, Sc, and Y. (© 2008 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)

Influence of hydrogenation on the electrical and optical properties of CdO thin films

The electrical and optical properties of CdO films post-annealed in hydrogen atmosphere for different durations (15 min, 30 min and 60 min) were studied. The prepared films were subjected to structural characterization by the x-ray diffraction method and optical characterization by the UV–VIS–NIR absorption spectroscopy method. Experimental data indicate that annealing in H2-atmosphere slightly compresses the CdO unit cell and widens the energy gap of CdO from 2.31 eV to 2.42 eV via a Burstein–Moss energy level shift. The optical properties were easily explained within the framework of Hamberg et al band-to-band transitions and classical Drude theory. It was found that the greatest enhancement of electrical parameters that related to the transparent-conducting-oxide (TCO) function occurs by annealing in H2-atmosphere for 30 min when the resistivity decreases, the conduction carrier concentration increases and the mobility increases. The results of the present work are important from a technical point of view for TCO production.

Some Physical Properties of CdO Thin Films Used as Window Material in Photovoltaic Solar Cells#

CdO thin films which can be used in photovoltaic solar cells as window material were obtained on glass substrates at 250°C and 300°C substrate temperatures using Ultrasonic Spray Pyrolysis (USP) technique. The electrical, optical, structural, and surface properties of the films were investigated for two different substrate temperatures. After all investigations, it is concluded that, the CdO thin films can be used in photovoltaic solar cells as window materials and cell efficiencies can be increased using different growth parameters. #Contributed by the Organizing Committee for the First International Exergy, Energy and Environment Symposium (IEEES-1). Article presented at IEEES-1, Izmir, Turkey, 13–17 July 2003. Manuscript received by IJGE on 2003-12-01; final revision received on 2004-03-12. Corresponding guest editors: I. Dincer and A. Hepbasli.

Oxygen partial pressure dependence of the structural properties of CdO thin films deposited by a modified reactive vacuum evaporation process

Thin films of cadmium oxide were thermally deposited on glass substrates at partial pressures of oxygen, pO 2 in the range 1.33×10 −2 to 0.133 Pa at a substrate temperature of 160 °C. Energy dispersive analysis of X-ray fluorescence (EDAX) revealed that the CdO films deposited at pO 2 value of 4.00×10 −2 Pa were nearly stoichiometric. X-ray diffractometry (XRD) confirmed the polycrystalline nature of the film structure. All the films showed an fcc structure of the NaCl-type, as the dominant phase. The films exhibited preferred orientation along the (1 1 1) diffraction plane. The texture coefficients calculated for the various planes at different oxygen partial pressures ( pO 2) indicated that the maximum preferred orientation of the films occurred along the (1 1 1) plane at an oxygen partial pressure of 4.00×10 −2 Pa. This was interpreted in terms of oxygen chemisorption and desorption processes. The lattice parameters determined from the diffraction peaks were in the range 4.655–4.686 Å. The average lattice parameter a 0 found by extrapolation using the Nelson–Riley function was 4.696 Å. Both the lattice parameter and the crystallite size were found to increase with increased partial pressure of oxygen. On the other hand, the strain and dislocation density were found to decrease as the partial pressure of oxygen was raised. A maximum (80%) in the optical transmittance at λ=600 nm and minimum in the electrical resistivity (9.1×10 −4 Ω cm) of the films occurred at an optimum partial pressure of oxygen of 4.00×10 −2 Pa. The results are discussed.