Annealing effect on the property of ultraviolet and green emissions of ZnO thin films

Kang, Hong Seong; Kang, Jeong Seok; Kim, Jae Won; Lee, Sang Yeol

doi:10.1063/1.1633343

Cited by 559 publications

(177 citation statements)

References 34 publications

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“…Interestingly, a new band at 405 nm emerged in the ZnO NSs annealed at or above 800°C, which was due to the formation of Zn 2 SiO 4 composites. 30 This band became stronger as the annealing temperature increased, as observed in the XRD results and previously discussed. The DBE band was also fitted with the Gaussian function to find the total integrated intensity of the band.…”

Section: Pl Spectroscopysupporting

confidence: 70%

Significance of postgrowth processing of ZnO nanostructures on antibacterial activity against gram-positive and gram-negative bacteria

Mehmood¹,

Ismail²,

Mirza³

et al. 2015

IJN

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In this work, we highlighted the effect of surface modifications of one-dimensional (1D) ZnO nanostructures (NSs) grown by the vapor–solid mechanism on their antibacterial activity. Two sets of ZnO NSs were modified separately – one set was modified by annealing in an Ar environment, and the second set was modified in O 2 plasma. Annealing in Ar below 800°C resulted in a compressed lattice, which was due to removal of Zn interstitials and increased O vacancies. Annealing above 1,000°C caused the formation of a new prominent phase, Zn 2 SiO 4 . Plasma oxidation of the ZnO NSs caused an expansion in the lattice due to the removal of O vacancies and incorporation of excess O. Photoluminescence (PL) spectroscopy was employed for the quantification of defects associated with Zn and O in the as-grown and processed ZnO NS. Two distinct bands were observed, one in the ultraviolet (UV) region, due to interband transitions, and other in the visible region, due to defects associated with Zn and O. PL confirmed the surface modification of ZnO NS, as substantial decrease in intensities of visible band was observed. Antibacterial activity of the modified ZnO NSs demonstrated that the surface modifications by Ar annealing limited the antibacterial characteristics of ZnO NS against Staphylococcus aureus . However, ZnO NSs annealed at 1,000°C or higher showed a remarkable antibacterial activity against Escherichia coli . O 2 plasma–treated NS showed appreciable antibacterial activity against both E. coli and S. aureus . The minimum inhibition concentration was determined to be 0.5 mg/mL and 1 mg/mL for Ar-annealed and plasma-oxidized ZnO NS, respectively. It was thus proved that the O content at the surface of the ZnO NS was crucial to tune the antibacterial activity against both selected gram-negative ( E. coli ) and gram-positive ( S. aureus ) bacterial species.

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Section: Pl Spectroscopysupporting

confidence: 70%

Significance of postgrowth processing of ZnO nanostructures on antibacterial activity against gram-positive and gram-negative bacteria

Mehmood¹,

Ismail²,

Mirza³

et al. 2015

IJN

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“…The broadening of violet-blue emission peak could be attributed to hybridization of various defect states induced by the non-equilibrium ball milling method of preparation and size distribution. In addition, a much weaker peak is located at 550 nm which is attributed to the surface defects from oxygen vacancies or Zn i [23]. Vanheusden et al [24] found that oxygen vacancies are responsible for the green luminescence in ZnO.…”

Section: Resultsmentioning

confidence: 99%

Intense violet–blue emission and paramagnetism of nanocrystalline Gd3+ doped ZnO ceramics

et al. 2015

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Nanocrystalline Zn 1x Gd x O (x = 0, 0.02, 0.04, 0.06, and 0.08) ceramics were synthesized by ball milling and subsequent solid-state reaction. The transmission electron microscopy (TEM) micrograph of as synthesized samples revealed the formation of crystallites with an average diameter of 60 nm, and the selected area electron diffraction (SAED) pattern confirmed the formation of wurtzite structure. A red shift in the band gap was observed with increasing Gd 3+ concentration. The photoluminescence of nanocrystalline Gd 3+ doped ZnO exhibited a strong violet-blue emission. Concentration dependence of the emission intensity of Gd 3+ in ZnO was studied, and the critical concentration was found to be 4 mol% of Gd 3+ . The Gd 3+ doped ZnO exhibited paramagnetic behavior at room temperature, and the magnetic moment increased with Gd 3+ concentration.

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“…The broad peak around 2.471 eV in the blue-green region is related to complex defect species, which is usually attributed to zinc interstitial or oxygen vacancies. 19 The peak in the ultraviolet region is related to excitonic emission. It can be seen that the tetrapods exhibited much lower defect state emissions than the multipods.…”

Section: Resultsmentioning

confidence: 99%

Shape controlled Sn doped ZnO nanostructures for tunable optical emission and transport properties

2013

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Pure and Sn doped ZnO nanostructures have been grown on SiO 2 /Si substrates by vapor-solid technique without using any catalysts. It has been found that the morphology of the nanostructures depend strongly on the growth temperature and doping concentration. By proper tuning of the growth temperature, morphology of pure ZnO can be changed from tetrapods to multipods. On the other hand, by varying the doping concentration of Sn in ZnO, the morphology can be tuned from tetrapods to flowerlike multipods to nanowires. X-ray diffraction pattern reveals that the nanostructures have a preferred (0002) growth orientation, and they are tensile strained with the increase of Sn doping in ZnO. Temperature-dependent photoluminescence characteristics of these nanostructures have been investigated in the range from 10 to 300 K. Pure ZnO tetrapods exhibited less defect state emissions than that of pure ZnO multipods. The defect emission is reduced with low concentration of Sn doping, but again increases at higher concentration of doping because of increased defects. Transport properties of pure and Sn doped ZnO tetrapods have been studied using complexplane impedance spectroscopy. The contribution from the arms and junctions of a tetrapod could be distinguished. Sn doped ZnO samples showed lower conductivity but higher relaxation time than that of pure ZnO tetrapods. C 2013 Author(s)

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Annealing effect on the property of ultraviolet and green emissions of ZnO thin films

Cited by 559 publications

References 34 publications

Significance of postgrowth processing of ZnO nanostructures on antibacterial activity against gram-positive and gram-negative bacteria

Significance of postgrowth processing of ZnO nanostructures on antibacterial activity against gram-positive and gram-negative bacteria

Intense violet–blue emission and paramagnetism of nanocrystalline Gd3+ doped ZnO ceramics

Shape controlled Sn doped ZnO nanostructures for tunable optical emission and transport properties

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