Effect of annealing temperature on the structural and optical properties of ZnO thin films prepared by RF magnetron sputtering

Daniel, Georgi P.; Justinvictor, V. B.; Nair, Prabitha B.; Joy, K.; Koshy, Peter; Thomas, P.V.

doi:10.1016/j.physb.2010.01.039

Cited by 78 publications

(38 citation statements)

References 25 publications

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“…Annealing of ZnO nano-crystals at higher temperatures have been found to alter the concentrations of the defects at the crystal surface. [42][43][44] The room temperature PL spectra of ZnO NRs with various surface defect densities are shown in Fig. 4, where all the ZnO NR samples exhibited emission in UV and visible region.…”

Section: Role Of Surface Defects In Photocatalytic Activity Of Au-znomentioning

confidence: 99%

Role of surface defects on visible light enabled plasmonic photocatalysis in Au–ZnO nanocatalysts

et al. 2015

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Visible light photocatalytic activity of the plasmonic gold-zinc oxide (Au-ZnO) nanorods (NRs) is investigated with respect to the surface defects of the ZnO NRs, controlled by annealing the NRs in ambient at different temperatures. IntroductionPhotocatalysis by nanostructured metal oxides has been extensively explored in the past due to the potential application in controlling the environmental pollutants for complete mineralization. AbstractVisible light photocatalytic activity of the plasmonic gold-zinc oxide (Au-ZnO) nanorods (NRs) is investigated with respect to the surface defects of the ZnO NRs, controlled by annealing the NRs in ambient at different temperatures. Understanding the role of surface defects on the charge transfer behaviour across a metal-semiconductor junction is vital for efficient visible light active photocatalysis. Au nanoparticles (NPs) are in situ deposited on the surface of the ZnO NRs having different surface defect densities, demonstrating efficient harvesting of visible light due to the surface plasmon absorption. The surface defects in the ZnO NRs are probed by using photoluminescence (PL) spectroscopy, X-ray photoemission spectroscopy (XPS), and photo-electro-chemical current-voltage measurements to study the photo-generated charge transfer efficiency across the Au-ZnO Schottky interface. The results show that the surface situated oxygen vacancy sites in the ZnO NRs significantly reduce the charge transfer efficiency across the Au-ZnO Schottky interfaces lowering the photocatalytic activity of the system. Reduction in the oxygen vacancy sites through annealing the ZnO NRs resulted in the enhancement of visible light enabled photocatalytic activity of the Au-ZnO plasmonic nanocatalyst, adding vital insight towards the design of efficient plasmonic photocatalysts. rsc_RA_c5ra16569e higher surface-to-volume ratios resulting in improved catalytic activity compared to their bulk counterparts. Metal oxides, for example, titanium dioxide (TiO 2 ), zinc oxide (ZnO), etc. are commonly used as photocatalysts, and are typically active under ultra-violet (UV) light due to their wide band gap energies. In recent times, designing photocatalysts that can be activated by visible light is one of the major research areas in order to efficiently and cost-effectively utilize them using the sunlight. Activation of wide bandgap metal oxide photocatalysts under visible light irradiation can be achieved in various ways, among which doping with transition metals, 4-6 creating intermediate defects, 7,8 sensitizing with visible light active dyes or other semiconductors materials, 9-11 narrow bandgap semiconductor coupling 12-14 etc. are some of the commonly used methods.Sensitizing the metal oxide photocatalysts with noble metal NPs to harvest visible light utilizing the surface plasmon resonance (SPR) absorption of the metallic NPs, and hence the name plasmonic photocatalysis, is emerging as a new area for designing smart photocatalysts. 15,16 Plasmonic photocatalysis typically involves distribution of ...

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Section: Role Of Surface Defects In Photocatalytic Activity Of Au-znomentioning

confidence: 99%

Role of surface defects on visible light enabled plasmonic photocatalysis in Au–ZnO nanocatalysts

et al. 2015

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“…The compressive strain was developed in the film with increase in film thickness. This may be due to the equilibrium conditions attained between the difference in the thermal expansion coefficients of the substrate and the film or the strain of the films after the coalescence of grains [19]. As film growth progresses with increase in sputtering time, more and more molecules reach the substrate.…”

Section: Experimental Studiesmentioning

confidence: 99%

Thickness dependence of structural, optical and luminescence properties of BaTiO3 thin films prepared by RF magnetron sputtering

Maneeshya¹,

Anitha²,

Thomas³

et al. 2015

J Mater Sci: Mater Electron

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BaTiO 3 thin films were deposited onto quartz substrates by RF magnetron sputtering. X-ray diffraction pattern showed the formation of BT thin films with a tetragonal structure with orientations along (101) plane. Average crystallite size increased from 12.52 to 14.87 nm as the film thickness increased from 207 to 554 nm. With the increase in film thickness, the structural disorder decreases and the crystalline quality of the films gradually improved. The film exhibited good adherence to the substrate and are crack free. X-ray photoelectron spectroscopy revealed the presence of barium, titanium and oxygen in BT film. An average transmittance of [80 % was observed for all the films. This high transmittance BT films in the visible region is suitable for various electro-optic applications. The transmittance spectra showed high UV-shielding properties. Optical band gap was found to decrease from 4.55 to 3.70 eV with increase of film thickness, whereas the refractive index was found to increase. The refractive index of the BT films can be tuned between 2.11 and 2.21 at 550 nm. The real and imaginary dielectric constants with increase in film thickness were investigated. The low dissipation factor of BT thin films makes it a promising material for frequency agile applications. The emission spectra of BT thin films consist of near band edge excitonic UV emission and defect related emission in the visible range. The PL emission bands in UV and visible region of BT thin films make them suitable for electro-optic devices and light emitters.

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“…-3.37 eV [6], large exciton binding energy (60 meV) [6] and also having good transparency, which are excellent parameters for optoelectronic devices.…”

Section: Introductionmentioning

confidence: 99%

Fabrication and characterization of electrodeposited and magnetron-sputtered thin films

Khan¹,

Pashaei²,

Bajwa³

et al. 2015

Int. J. CMEM

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The MnO-Zn thin films were fabricated by radio frequency (RF) magnetron sputtering and compared with pulse electrodeposition (PED) Zn thin films, doped with MnO and ZrO nanoparticles. Surface morphology, structural properties, chemical composition and corrosion resistance of these coatings were investigated by using scanning electron microscopy, X-ray diffraction (XRD), energy-dispersive X-ray spectroscopy, 3-D scanning interferometry and environmental chamber. Surface morphology and degree of crystallinity have different behaviours for different deposition methods. Pulse-coated films have polycrystalline structure with high surface roughness (R a ), whereas sputtered films are monocrystalline with reduced roughness (R a ). Corrosion tests of both RF sputter and PED films revealed that the distribution of corrosion products formed on the surface of sputter films were not severe in extent as in case of electrodeposited coatings. Results showed that the doping of ZrO nano-sized particles in Zn matrix and Mn-Zn composite films significantly improved the corrosion resistance of PED thin films. High electron mobility [7] and room temperature electrical conductivity of ZnO thin films make it perfect material for electronics equipment. Additional advantages of ZnO thin films and micro-nanostructure are abundance and non-toxicity of the ZnO material, low cast and quantum size effect. Depending on the application, tuning properties and band gap of ZnO is possible by doping another material such as: aluminum (Al), gallium (Ga), magnesium (Mg) and manganese (Mn).Also, there are advanced techniques of growing ZnO thin films and manufacturing such as metal organic chemical vapor deposition [8], radio frequency (RF) magnetron sputtering [9], sol-gel method and pulsed laser deposition [10]. Properties of ZnO thin films are investigated by using molecular beam epitaxy [11].Zinc plating is extensively used in corrosion protection of steel in many structural and general engineering applications. Zn coating on steel substrate provides with physical and mechanical properties as well as good corrosion resistance [12]. However, a high dissolution rate and low corrosion resistance limit the use of Zn coatings. In recent research and development activity on zinc-based alloy coatings, there is a growing interest in the use of Zn with various alloying elements like Mn and Zr. These elements (Mn and Zr) have an electrically, more negative potential (E°M n

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Effect of annealing temperature on the structural and optical properties of ZnO thin films prepared by RF magnetron sputtering

Cited by 78 publications

References 25 publications

Role of surface defects on visible light enabled plasmonic photocatalysis in Au–ZnO nanocatalysts

Role of surface defects on visible light enabled plasmonic photocatalysis in Au–ZnO nanocatalysts

Thickness dependence of structural, optical and luminescence properties of BaTiO3 thin films prepared by RF magnetron sputtering

Fabrication and characterization of electrodeposited and magnetron-sputtered thin films

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