Formation and Characterization of Co2O3 and Co2O3(1-x):Cux Thin Films (original) (raw)
Related papers
OPTICAL DISPERSION CHARACTERIZATION OF SPRAYED Co 2 O 3 :Cu THIN FILMS
Uniform and adherent cobalt oxideCo 2 O 3 andcopper doped cobalt oxide Co 2 O 3 :Cu films have been deposited by using spray pyrolysis technique (SPT) on glass substrates. For investigating the structure and optical properties of thin films, X-ray diffraction (XRD) and UV-vis spectra were used. Increasing dopant caused an increase in the crystal size. The optical properties and dispersion parameters of cobalt oxide have been studied as a function of Cu dopant concentration. Changes in direct optical band gap of cobalt oxide films were confirmed after doping,the optical energy gap Eg increased from 1.48 and 1.95 eV for the undoped Co 2 O 3 to 1.55 and 2.05 eV with increasing the doping concentration of Cu to 5%. The changes in dispersion parameters and Urbach tails were investigated. An increase in the doping concentration causes a decrease in the average oscillator strength from 45.60 to 25.32. The single-oscillator parameter has been reported.
Copper-doped cobalt oxide (Cu:Co3O4) films have been prepared by spray pyrolysis (SP) method onto glass substrate at (350) C with different copper doping concentrations (0%, 1%, 3%, 5%, 7%, 9%) M. Structural and optical properties of the films were studied by X-ray diffraction (XRD) and ultraviolet (UV-Visible) transmission spectra. The X-ray diffraction results revealed that the films consist of Co3O4 phase with perfect orientation (111) crystallite size variation with increasing Cu doping concentration (34.92, 34.02, 30.87, 30.81, 32.35, 34.04)nm respectively, and lattice constant was (8.065, 8.0668, 8.0692, 8.074, 8.0854, 8.0546)A . It is found from optical measurements that the transmition is inversely proportional with concentration, the absorption coefficient (α) at the fundamental absorption region was determined using the spectra data of transmittance. The tow allowed direct energy gaps were varied between (1.4 to 2.06) eV and they are decreasing with increasing the doping concentration. While the two indirect energy gaps were decrease as doping concentrations were increased with variation between (1.2 to 1.9) eV.
Surface morphology, optical properties and Urbach tail of spray deposited Co3O4 thin films
Journal of Materials Science: Materials in Electronics, 2019
Cobalt oxide (Co 3 O 4) thin films were deposited onto glass substrates by a simple spray pyrolysis technique using Co (CH 3 COO) 2 .4H 2 O as a precursor material. The as-deposited films were characterized using field emission scanning electron microscope (FESEM) and UV-visible spectrophotometer. FESEM images showed uniform and well-aligned nanofiber growth of Co 3 O 4 thin film. The average crystallite size was found to increase from 15 to 25 nm with the increase of substrate temperature. The increase in average crystallite size may be due to the agglomeration and recrystallization of cobalt oxide nanoparticles. The absorption peaks obtained at 355 nm and 540 nm were attributed to the transitions taking place between oxygen and cobalt charge transfer (O 2− → Co 3+ and O 2− → Co 2+). The energy band gap was found to decrease from 2.35 to 2.03 eV and Urbach energy (E u) increased from 0.73 eV to 0.84 eV with the increased substrate temperatures from 250 °C to 350 °C. The optical absorption coefficient exhibited an exponential dependence of photon energy following Urbach's rule, and Urbach tail was dependent on lattice defects. The direct band gap of the Co 3 O 4 thin film clearly showed a red shift with increasing temperature and provided an absorption favorable for bio-sensing applications.
Structural Characterization and Optical Properties of cobalt oxide Thin Films
A Sol-gel dip coating route has been employed to synthesize cobalt oxide thin films on glass substrates. The obtained films are characterized by X-ray diffraction (XRD), UV-VIS spectrophotometer, vibrating sample magnetometer (VSM), Scanning Electron Microscope and Fourier Transform Infra Red (FTIR) spectroscopy. The films are identified as Co 3 O 4 by FTIR. XRD further confirmed Co 3 O 4 phase. Upon increasing withdrawal speed of substrate, the transmission and band gap decreases due to increase in film thickness. Thin films show room temperature ferromagnetism and magnetic properties enhance by increasing thickness of thin films. SEM shows porous surface of films.
Thin Solid Films, 2019
Cobalt oxide films have been produced by chemical bath deposition technique at various bath temperatures for different deposition times onto glass substrates. The as-grown Co 3 O 4 films were annealed at 300°C for 1 h and investigated via x-ray diffraction, field emission scanning electron microscopy. The x-ray diffraction patterns have revealed that the annealed samples are polycrystalline with face-centered-cubic structure. The cubic phase is clearly seen in the form of long rods from micrographs. The band gap of the Co 3 O 4 thin films was determined using absorption spectra. The samples have exhibited direct transition with the band gap values lying in the range between E opt1 = 1.40-1.49 eV and E opt2 = 2.02-2.19 eV. The refractive index and extinction coefficient as a function of wavelength were investigated from reflectance spectrum by applying the envelope method. The optical parameters of the Co 3 O 4 film, such as dielectric constants, plasma frequency, and carrier concentration, were also evaluated. The electrical properties of the samples constructed planar structure have been measured in the dark at room temperature by applying the voltage values between 1 and 100 V.
Fabrication and characterization of nanocrystalline cobalt oxide thin films
Materials Research Bulletin, 2001
A simple solution growth route has been employed to synthesize nanocrystalline cobalt oxide thin films on glass substrates. The obtained films were characterized by X-ray diffraction and FTIR spectroscopy. The as-deposited films were identified as a mixture of different phases of Co(OH)2, while the annealed ones as Co3O4. The absorption of the annealed films gradually decreases with an increase of the wavelength in the 310–820 nm region. Upon annealing, the absorption coefficient decreases. The calculated band gap energy from optical absorption data for annealed films is 2.2 eV. The as-deposited thin films are dielectric, while the post-deposition heat-treated ones are characterized by resistivity of several MΩs/cm2 at room temperature.
Structural and optical proprieties of doped cobalt oxide: Cu Co3−O4 (x= 0.0; 0.1; 0.2; 0.4; and 0.6)
Optik, 2015
Copper cobaltite oxides of formula Cu x Co 3−x O 4 (x = 0.0; 0.1; 0.2; 0.4 and 0.6) were synthesized by hydrothermal conditions using polyethylene-glycol-400 (PEG-400) as surfactant. The as-prepared samples are characterized by X-ray diffraction (XRD) and scanning electron microscopy (SEM). Rietveld fitted patterns confirm the formation of cubic spinel structure with Fd-3m space group. Particle size was determined from the XRD peak broadening analysis. The Cu-doping effect on the structural and optical properties of the copper cobaltite oxides was investigated. Phase purity of Cu x Co 3−x O 4 was confirmed by X-ray diffraction studies. XRD results reveal that the lattice parameters and the theoretical density (d th) were found to increase with Cu-substitution. The direct and indirect band gap energies were found to decrease with increasing Cu-content from 1.72 eV (x = 0) to 1.39 eV (x = 0.6) and from 1.75 eV for x = 0 (Co 3 O 4) to 1.40 eV for x = 0.6 (Cu 0.6 Co 2.4 O 4) respectively, indicating a red shift trend when the Cu-content increases.
Journal of Electronic Materials, 2019
The effects of cobalt (Co)-doping (0 at%, 2 at%, 4 at%, 6 at%, and 10 at%) on the structural, morphological, electrical, and optical characteristics of spraydeposited nanostructured copper oxide (CuO) thin films were investigated. Xray diffraction patterns revealed that the crystallite size is subject to a constant reduction with an increase in the doping concentration. Based on fieldemission scanning electron microscopy images, no change was observed for the grain shapes; however, the grain size decreased with an increase in the doping concentration. Furthermore, doping Co led to a conversion from a fairly weak p-type conductivity for the undoped CuO thin film (3.42 9 10 À4 X cm) to a considerable n-type conductivity for the 10 at% Co-doped CuO (CuO:Co) film (4.20 9 10 À1 X cm). Although the mobility of the resulting films decreased with Co doping, it seems that the significant enlargement in free electron carrier concentration is responsible for conductivity transition and improvement. Finally, the bandgap values were estimated using experimental data of transmittance and reflectance.
In this work, Cobalt oxide thin films were prepared using chemical spray paralysis. The thin filmswere precipitated on glass substrates and were heated for various temperatures (100, 150, 200, 250 and 300 ο C). The annealed Cobalt oxide thin films were characterized using UV-visible spectroscopy. The optical properties of the prepared films were determined including Energy gap, Absorption coefficient, Extinction coefficient and refractive index. The annealing temperatures effect on the thickness of the films was profound. Whereas, the energy band gap were slightly affected by the selected annealing temperatures and the energy band gap were found to be 2. 70, 2.60, 2.60, 2.60 and 2.57, respectively. The absorption coefficient, extinction coefficient and refractive index were increased with annealing temperature.