Article

Growth and characterization of molybdenum oxide nanorods by RF magnetron sputtering and subsequent annealing

Journal of Physics D Applied Physics (Impact Factor: 2.72). 09/2009; 42(17). DOI: 10.1088/0022-3727/42/17/175305

ABSTRACT

High-densely packed and uniformly distributed molybdenum oxide nanorods have been grown onto glass substrates by RF magnetron sputtering and subsequent annealing in an oxygen atmosphere. A two-step growth mechanism (sputtering redeposition and enhanced rearrangement during annealing) for the formation of MoO3 nanorods has been proposed. The morphological, structural, optical and electrical properties of the nanorods have been investigated systematically using atomic force microscopy, scanning electron microscopy, x-ray diffraction, micro-Raman, UV-visible, photoluminescence (PL) spectroscopy and dc resistivity studies. The nanorods in the as-sputtered film and the film annealed at 473 K are amorphous in nature. However, the nanorods in the films annealed at 573 and 673 K exhibit the presence of monoclinic Mo 8O23 and orthorhombic MoO3, respectively. Vibrational analysis of the molybdenum and oxygen atoms in the nanorods is carried out by micro-Raman spectra. The nanorods show room temperature PL in the UV-visible region. The PL emission is found to be strongly enhanced by post-deposition annealing. The low temperature resistivity measurement is done on the as-deposited film; the activation energy and polaron hopping energy for electrical conduction are calculated. The MoO3 nanorods are expected to exhibit enhanced functionality, particularly in nanoscale, photochromic and gas sensing applications.

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    • "In this regard, MoO 3 that exhibit optical band gap between 2.3 and 2.98 eV depend on the nanostructure morphology and fabrication method would be an interesting candidate for visible photocatalytic applications [51]. Chithambararaj et al. synthesized hexagonal rod shaped MoO 3 and studied the photodegradation of methylene blue (MB) under irradiation of visible or UV light [52]. "
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    ABSTRACT: Thermodynamically stable α-MoO3 nanoplates were synthesized using organic aliphatic acids as structure controlling agents and investigated photocatalytic degradation of methylene blue (MB) and rhodamine blue (Rh-B) in presence of sun light. Three different organic aliphatic acids, citric acid (CA), tartaric acid (TA) and ethylene diamine tetra-acetic acid (EDTA), were employed to control morphologies. CA and TA predominantly produced extended hexagonal plates where EDTA gave nanorods as well as nanoplates. PXRD studies confirmed the formation of α-MoO3 nanoparticles. HR-TEM and FE-SEM reveal the formation of plate morphologies with 20–40 nm thickness, 50–100 nm diameter and 600 nm lengths. The different morphologies of α-MoO3 nanoparticles lead to the tunable optical band gap between 2.80 and 2.98 eV which was obtained from diffused reflectance spectra (DRS). Interestingly, the synthesized α-MoO3 nanoplates exhibited strong photocatalytic degradation of MB and Rh-B up to 99% in presence of sun light without using any oxidizing agents.
    Full-text · Article · Jan 2016 · Materials Research Bulletin
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    • "It is also a promising candidate as a back contact layer for cadmium telluride solar cells in superstrate configuration because of its high work function, which possibly reduces the back contact barrier [7]. Various physical thin film deposition techniques such as thermal evaporation [8] [9], electron beam evaporation [10] [11], pulsed laser deposition [12] [13], and sputtering [14] [15] [16] [17] [18] and chemical methods such as electrodeposition [19], chemical vapour deposition [20], spray pyrolysis [21] [22], and sol-gel process [23] [24] [25] were employed for the growth of MoO 3 films. Among these films deposition techniques, magnetron sputter deposition is an industrially practiced technique for the growth of oxide films. "
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    ABSTRACT: Molybdenum oxide (MoO3) films were deposited on glass and silicon substrates held at temperature 473 K by RF magnetron sputtering of molybdenum target at various oxygen partial pressures in the range mbar. The deposited MoO3 films were characterized for their chemical composition, crystallographic structure, surface morphology, chemical binding configuration, and optical properties. The films formed at oxygen partial pressure of mbar were nearly stoichiometric and nanocrystalline MoO3 with crystallite size of 27 nm. The Fourier transform infrared spectrum of the films formed at mbar exhibited the characteristics vibrational bands of MoO3. The optical band gap of the films increased from 3.11 to 3.28 eV, and the refractive index increased from 2.04 to 2.16 with the increase of oxygen partial pressure from to mbar, respectively. The electrochromic performance of MoO3 films formed on ITO coated glass substrates was studied and achieved the optical modulation of about 13% with color efficiency of about 20 cm2/C.
    Full-text · Article · Sep 2013
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    • "As increasing the thickness from 10 to 15 nm, the JSC decreases from 8.87 to 8.18 mA cm-2 and the fill factor (FF) decreases from 0.315 to 0.307, and as a result, the PCE decreases from 1.01% to 0.90%. Previous works had reported that MoO3 has a quite high electrical resistivity (>109 Ω cm) [13-15]. Therefore, the deterioration of the IOSC performance may be induced by a higher intrinsic resistance of the MoO3 with 15 nm, restraining the charge transport from the active layer to Al electrodes. "
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    ABSTRACT: ABSTRACT: Flake-like Al-doped ZnO (AZO) nanostructures including dense AZO nanorods were obtained via a low-temperature (100°C) hydrothermal process. By doping and varying Al concentrations, the electrical conductivity (σ) and morphology of the AZO nanostructures can be readily controlled. The effect of σ and morphology of the AZO nanostructures on the performance of the inverted organic solar cells (IOSCs) was studied. It presents that the optimized power conversion efficiency of the AZO-based IOSCs is improved by approximately 58.7% compared with that of un-doped ZnO-based IOSCs. This is attributed to that the flake-like AZO nanostructures of high σ and tunable morphology not only provide a high-conduction pathway to facilitate electron transport but also lead to a large interfacial area for exciton dissociation and charge collection by electrodes.
    Full-text · Article · Oct 2011 · Nanoscale Research Letters
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