Structural, optical, and electrical properties of Yb-doped ZnO thin films prepared by spray pyrolysis method

Yb-doped ZnO thin films were prepared on glass substrates by spray pyrolysis technique in order to investigate the insertion of Yb ions in the ZnO matrix and the related optical properties of the films. The molar ratio of Yb in the spray solution was varied in the range of 0-5 at. %. X-ray diffraction patterns showed that the undoped and Yb-doped ZnO films exhibit the hexagonal wurtzite crystal structure with a preferential orientation along [002] direction. No secondary phase is observed in Yb-doped ZnO films. All films exhibit a transmittance between 75 and 90% in the visible range with a sharp absorption onset about 375 nm corresponding to the fundamental absorption edge at 3.3 eV. The photoluminescence measurements show a clear luminescence band at 980 nm that is characteristic of Yb(3+) transition between the electronic levels (2)F(5/2) and (2)F(7/2). This is an experimental evidence for an efficient energy transfer from ZnO matrix to Yb(3+). Hall effect measurements showed low resistivities and high carrier mobilities which makes these films of interest to photovoltaic devices.This work is supported by the program interdisciplinaire énergie du CNRS Grant No. PE10-2.1.2-2

Thin films for CIS solar tells

In this paper, we present our Studies on three materials CuInS2, ZnO and CdS which can be used to elaborate CIS solar cells. For instance, we have used spray pyrolysis and chemical bath deposition to prepare these compounds. Sprayed CuInS2 thin films have exhibited a preferential (112) orientation with chalcopyrite structure and p type conductivity. Their energy gap value was around 1.45 eV, which perfectly matches the solar spectrum. We also studied the Cu:In :S ratio effect on its properties. Sprayed Undoped and indium-doped ZnO films were highly transparent since their energy gap value was 3.2eV. The films were polycrystalline and exhibited an hexagonal wurtzite-type structure. Their orientation was modified by an adequate indium doping which leads to a resistivity value of about 10-3 Wcm. Homogeneous and strongly adherent CdS very thin layers of about 70 nm were prepared by CBD Process. The obtained films have showed preferential orientation which changes from (002) to (101) with growth temperature and annealing treatment. CdS was very resistive with an energy gap around 2.37eV.In this paper, we present our Studies on three materials CuInS2, ZnO and CdS which can be used to elaborate CIS solar cells. For instance, we have used spray pyrolysis and chemical bath deposition to prepare these compounds. Sprayed CuInS2 thin films have exhibited a preferential (112) orientation with chalcopyrite structure and p type conductivity. Their energy gap value was around 1.45 eV, which perfectly matches the solar spectrum. We also studied the Cu:In :S ratio effect on its properties. Sprayed Undoped and indium-doped ZnO films were highly transparent since their energy gap value was 3.2eV. The films were polycrystalline and exhibited an hexagonal wurtzite-type structure. Their orientation was modified by an adequate indium doping which leads to a resistivity value of about 10-3 Wcm. Homogeneous and strongly adherent CdS very thin layers of about 70 nm were prepared by CBD Process. The obtained films have showed preferential orientation which changes from (002) to (101) with growth temperature and annealing treatment. CdS was very resistive with an energy gap around 2.37eV

ZnO layers prepared by spray pyrolysis

Highly transparent undoped and indium doped ZnO thin films have been grown on glass substrates by using the spray pyrolysis process. Conditions of preparation have been optimized to get good quality and reproducible films with required properties. Polycrystalline films with an hexagonal Wurtzite-type structure were easily obtained under the optimum spraying conditions. Both of samples have shown high transmission coefficient in the visible and infrared wavelength range with sharp absorption edge around 380 nm which closely corresponds to the intrinsic band-gap of ZnO (3.2 eV). Orientation and crystallites size were remarkably modified by deposition temperature and indium doping

Absorption Enhancement in Thin-Film Solar Cells with Perforated Holes

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Sodium doping mechanism on sol-gel processed kesterite Cu2ZnSnS4 thin films

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Investigation of the structural, optical and electrical properties of Nd-doped ZnO thin films deposited by spray pyrolysis

Neodymium-doped zinc oxide (NZO) thin films were deposited on glass substrates by spray pyrolysis technique. X-ray diffraction patterns have shown that both undoped and Nd-doped ZnO films exhibit the hexagonal wurtzite crystal structure with a preferential orientation along [0 0 2] direction. The effective doping concentration has been determined by Rutherford backscattering measurements showing that the neodymium is not incorporated easily into ZnO host matrix. The surface roughness was shown to increase with Nd doping. NZO films are highly transparent in the visible region. The lowest electrical resistivity value of about 4.0 10−2 Ω cm was obtained for 1% Nd effective doping

Structural, optical, spectroscopic and electrical properties of Mo-doped ZnO thin films grown by radio frequency magnetron sputtering

Undoped and Mo-doped ZnO (2% Mo) films about 1 mu m thick were deposited by radio-frequency magnetron sputtering on Si(100) and glass substrates at 30 and 300 degrees C. X-ray diffraction patterns show that all films exhibit the hexagonal wurtzite crystal structure with a preferred orientation of the crystallites along the [002] direction. Plane view and cross-section transmission electron microscopy observations showed that the films present a columnar growth. Rutherford backscattering spectrometry indicates that Mo is homogeneously distributed inside the films. Scanning electron microscopy and atomic force microscopy show that Mo doping leads to a reduction of the grain size and surface roughness. According to X-ray photoelectron spectroscopy measurements, the valence of the Mo ions in the ZnO matrix is +5 and +6. Optical measurements in the UV-Visible range show a transmittance increasing from about 60 to 80% when increasing the wavelength from 400 to 800 nm. A sharp absorption onset is observed at about 375 nm corresponding to the fundamental absorption edge of ZnO at 3.26 eV. This gap value remains unchanged upon Mo doping. The Hall effect measurements carried out at room temperature show that both undoped and Mo-doped ZnO films present an n-type conduction. The 2% Mo doping increases the carrier concentration and decreases the resistivity measured in pure ZnO by about three orders of magnitude. A comparison with 2% Al-doped ZnO films grown in the same conditions underlines the important role of the preparation conditions on the transport properties of ZnO based transparent conductive oxides. (C) 2014 Elsevier B.V. All rights reserved