Papers by Keyword: Cuprous Oxide

Abstract: Cuprous oxide (Cu₂O) has a high optical absorption coefficient and favourable electrical properties, which make Cu₂O thin films attractive for photovoltaic applications. Using reactive radio-frequency magnetron sputtering, high quality Cu₂O thin films with good carrier transport properties were prepared. This paper presents the characteristics of Cu₂O thin films that were sputter deposited on quartz substrates and subjected to post-deposition rapid thermal annealing. The thickness of the thin films and the optical constants were determined by ellipsometry spectroscopy (SE). The optical transmittance increased in lower wavelength region after annealing at 900 ̊C in rapid thermal annealing (RTA). The structural and morphological properties of the Cu₂O thin films were investigated by electronic scanning microscopy (SEM) and atomic force microscopy (AFM), whereas elemental analysis was performed by X-ray fluorescence spectroscopy (XRF). The carrier mobility, carrier density and film resistivity were changed after post-deposition rapid thermal annealing from respectively ~14 cm2/Vs, ~2.3 x 10¹⁵ cm^-3 and ~193 Ωcm for the as-deposited Cu₂O film to ~49 cm2/Vs, ~5.0 x 10¹⁴ cm^-3 and ~218 Ωcm for the annealed Cu₂O film. The investigation suggests that the sputter-deposited Cu₂O thin films have good potential for application as absorber layers in solar cells.

Abstract: Metal oxides are widely used as components in photovoltaic cells such as transparent conducting front electrodes or electron-transport layers, while only few metal oxides have been used as light absorbers. In this study, cuprous oxide was modified by anchoring TSCuPc dye molecules via potentiostatic electrodeposition approach. Fourier Transform Infrared Spectroscopy results display the different vibration peaks for S=O bond and C-N present in the TSCuPc modified Cu₂O deposits signifying the attachment of TSCuPc on Cu₂O. The highest absorbance peaks of Cu₂O and TSCuPc at approximately 420 nm and 650 nm respectively was observed when 20uM of TSCuPc was added in the electrodeposition solution. Scanning Electron Microscopy reveals the formation of Cu₂O film and formation of secondary submicron size structures with the addition of TSCuPc. The surface morphology of the secondary structures changes as the concentration TSCuPc increases. With the aforementioned results, it was verified that TSCuPc can be anchored to Cu₂O via electrochemical route which could pave way in developing materials with high absorption in visible light applicable for optoelectronic devices.

Abstract: CuO_x powders with diff erently shaped particles were firstly prepared via an electrochemical method by oxidation and dispersion of copper electrodes in an electrolyte solution under pulse alternating current (PAC). By means of X-ray diffraction (XRD) and scanning electron microscopy (SEM) the current density is found to have an influence on the morphology and composition of CuO_x particles. Photocatalytic efficiency of CuO_x towards methyl orange (MO) degradation under visible light was investigated. The prepared polyhedral particles show the best photocatalytic activity of 81 % towards MO comparing to octahedral and spherical particles with 70 and 61 %, respectively.

Abstract: This work demonstrates the fabrication of Cu₂O thin film onto a fluorine-doped tin oxide (FTO) glass substrate via electrodeposition method which was conducted in a solution containing copper (II) acetate monohydrate and lactic acid. While varying the deposition time ranging up to 80 minutes, the solution was kept constant at solution temperature of 40°C, solution pH 6.5 and current density-0.3 mA/cm². The characteristics of electrodeposited Cu₂O were investigated via x-ray diffractometer (XRD), field emission scanning electron microscopy (FESEM), atomic force microscopy (AFM), current-voltage (I-V) test and surface profiler. The XRD results showed the intensity peak of Cu₂O corresponded to reflection (111) increased when the deposition time increased. The topological characteristics from AFM characterization showed the increment of surface roughness decreased as the time increased from 5 to 60 minutes. However, the surface roughness decreased when the time reached 70 and 80 minutes. I-V characteristics of all electrodeposited Cu₂O showed Ohmic behaviours indicating the successful fabrication of n-Cu₂O thin film. From this study, the significant effect of deposition time of Cu₂O was clearly observed and plays an important role in providing mechanism growth of the film.

Abstract: Cuprous oxide (Cu₂O) thin films were formed onto indium tin oxide (ITO) coated glass substrate by sol-gel spin coating technique using different additives namely polyethylene glycol and ethylene glycol. It was found that the organic additives added had an important influenced on the formation mechanism of Cu₂O films and lead to different microstructures and optical properties. The films were characterized by X-ray diffraction (XRD), field emission scanning electron microscopy (FESEM) and ultraviolet-visible spectroscopy (UV-Vis). Based on the FESEM micrographs the grain size of film prepared by polyethylene glycol has smallest grain of about 83 nm with irregular shape. The highest optical absorbance film was obtained by the addition of polyethylene glycol.

Abstract: Cuprous oxide catalyst was prepared and applied as photocatalist to treat chromium (VI) in wastewater, and the photocatalytic activity of the cuprous oxide was studied. The optimal conditions for the treatment was as follows: the pH of wastewater was 3, the amount of catalysts was 0.3 g/L, the reaction temperature was 60°C. Under the optimal conditions, the removal rate of chromium (IV) in wastewater reached 50% in the presence of cuprous oxide catalyst.

Abstract: The electrochemical reduction of carbon dioxide (CO₂) using WO₃ decorated Cu₂O (Cu₂O-WO₃) composite was investigated in KHCO₃ solution saturated with CO₂ by cyclic voltammetry. The electrode which shows a good ability of electrochemical CO₂ reduction chosed nickel foam as substrate with Cu₂O and Cu₂O-WO₃deposited on it. WO₃ modification can improve the ability .The results of cyclic voltammetry show that catalytic activity of Cu₂O-WO₃ mixture is affected by effective contact area .

Abstract: Cu wires were heated by electric currents to fabricate Cu₂O thin films. The films were successfully deposited on glass substrates placed above the wires at air pressures in the range of 100 - 40 Pa. Then the films were annealed in a controlled atmosphere and investigated the crystallinity, morphology and the time response to illumination of the films. After annealing at 800 °C at atmospheric pressure with oxygen partial pressure of 12 Pa, the crystallinity was increased and the time response of photoconduction was successfully improved.

Abstract: Cu₂O-MoO₃ composites has been successfully fabricated by solution-phase reducing method at room temperature. All the powders were characterized by X-rays diffraction (XRD) and scanning electron microscopy (SEM), and explored the catalytic activity for the photocatalytic degradation of methyl orange. The effect of different factors on the degradation was investigated. The best reaction conditions were found out. The results demonstrated that initial concentration of methyl orange is 5 mg/L, the pH is 4, the catalyst dosage is 0.38 g/L and the H2O2 is 1.8 mL, the degradation rate of methyl orange is as high as 95.4% after 30 minutes simulated natural light irradiation.

Abstract: Although copper have better electrical properties than aluminum such as low resistivity and high electro-migration resistivity, aluminum has been used as an interconnect material due to the difficulty in Cu dry etching. Since CMP process has been adapted to the semiconductor fabrication, Cu became the choice of materials for interconnection. However, copper CMP process introduces new defects on the surface such as slurry particle, organic residue, scratch and corrosion [1].