Great blue-shift of luminescence of ZnO nanoparticle array constructed from ZnO quantum dots

Wang, Nengwen; Yang, Yuhua; Yang, Guowei

doi:10.1186/1556-276x-6-338

Cited by 49 publications

(21 citation statements)

References 32 publications

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“…Assuming crystallite size effects only, one would obtain D ~5 nm for the ZnO films and D ~ 35 nm for the submicrospheres. Furthermore, for a crystallite size of ~5 nm, a relatively large blueshift of the UV emission band in the PL spectra would be expected [4], placing the band maximum in the 365-369 nm range [32,33]. As shown in the next subsection, the UV PL band maximum wavelength position is 376 nm.…”

Section: Morphology and Crystalline Structurementioning

confidence: 79%

Metastability effects on the photoluminescence of ZnO nano-micro structures grown at low temperature and influence of the precursors on their morphology and structure

González¹,

Marin²,

Tirado³

et al. 2018

Mater. Res. Express

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Nanocrystalline ZnO films were grown on silicon substrate by hydrothermal synthesis at 125 °C, using diethanolamine as additive. A powder containing ZnO spheres, with diameters between 100 to 200 nm and formed by aggregation of ZnO nanoparticles, was also obtained as a secondary reaction product. The samples were studied by scanning electron microscopy, X-ray diffraction and photoluminescence (PL) spectroscopy. The effects of the [diethanolamine]/[Zn 2+ ] molar ratio on morphological, structural and optical properties were studied, as well as the effect of laser illumination (λ=325 nm) and annealing treatment on photoluminescence properties. The film samples exhibited a compact columnar structure, with thickness between 180 to 210 nm, which were not strongly affected by the diethanolamine concentration. The X-ray diffraction patterns from the films evidenced preferred orientation along the c-axis of the ZnO wurzite structure; while the nanospheres did not show any preferential crystalline direction. The PL spectra from the films showed large initial UV emission and a weak defect band centered in the yellow. A PL evolution while the samples were UV illuminated was observed. The relaxation of metastable phases (formed during the low temperature growth) involving the creation of point defects, is suggested. The predominance of the

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Section: Morphology and Crystalline Structurementioning

confidence: 79%

Metastability effects on the photoluminescence of ZnO nano-micro structures grown at low temperature and influence of the precursors on their morphology and structure

González¹,

Marin²,

Tirado³

et al. 2018

Mater. Res. Express

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“…The band gaps determined for ZnO and doped ZnO were 3.60 (ZnO), 3.44 (ZnO-Al), and 3.39 (ZnO-Ni) eV. This shift to the red may be attributed to quantum confinement effects [19,32]. Most authors have observed that transition metal ions might additionally introduce d-d transitions into the UV-Vis spectra if the samples are present in a suitable oxidation state [1,17,33].…”

Section: Structure From Xrd Patterns and Raman Spectramentioning

confidence: 99%

Synthesis and Characterization of Nanocrystalline ZnO Doped with Al3+ and Ni2+ by a Sol–Gel Method Coupled with Ultrasound Irradiation

et al. 2018

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Zinc oxide is one of the most important semiconducting metal oxides and one of the most promising n-type materials, but its practical use is limited because of both its high thermal conductivity and its low electrical conductivity. Numerous studies have shown that doping with metals in ZnO structures leads to the modification of the band gap energy. In this work, Al-doped ZnO, Ni-doped ZnO, and undoped ZnO nanocrystalline powders were prepared by a sol–gel method coupled with ultrasound irradiation, and the results show the influence of Al3+ and Ni2+ ions in the ZnO network. The doping concentrations in ZnO of 0.99 atom % for ZnO–Al and 0.80 atom % for ZnO–Ni were obtained by X-ray Fluorescence (XRF). X-ray Diffraction (XRD) and Raman Spectroscopy showed a decreased intensity and broadening of main peaks, indicating metallic ions. The crystallite size of the sample was decreased from 24.5 nm (ZnO) to 22.0 nm (ZnO–Al) and 21 nm (ZnO–Ni). The textural and morphological properties were analyzed via Nitrogen Adsorption (BET method) and Field Emission Scanning Electron Microscopy (FESEM).

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“…The peak at 368 nm (3.37eV) is characteristic of neutral-donor-bound-exciton (D0X) emission (Zhanget al, 2004;Ashrafi et al, 2004).The appearance of a weak shoulder at ~2.89 eV (violet region) is attributed to radiative recombination from intrinsic defects in the ZnO dots. Quantum confinement effects are not observed in the PL spectra because the size of the QDs is considerably larger than the exciton Bohr radius of ZnO (2.34 nm) (Wang et al, 2011). …”

Section: Resultsmentioning

confidence: 99%

ZnO QDs Deposited on Si by Sol-Gel Method: Role of Annealing Temperature on Structural and Optical Properties

Al-Azawi

Al-Asedy²,

Bidin³

et al. 2016

MAS

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Zinc acetate, propanol, and ethanolamine are used to synthesize ZnO quantum dots (QDs) via the sol-gel method. Spin coating at 220°C is then employed to prepare ZnO thin films consist of QDs. The effects of thermal annealing temperature on the structural and optical properties of the samples are investigated. The prepared QDs are characterized using X-ray diffraction (XRD), field emission scanning electron microscopy (FESEM), and photoluminescence spectroscopy (PL). XRD patterns reveal the crystalline nature of samples existing in the hexagonal wurtzite phase. Increasing annealing temperatures bring about changes to the crystal orientation through the c-axis and increase the size of the QDs from ~10 nm to ~22 nm; this increment can be explained by a coarsening mechanism and the Ostwald ripening process. The observed broadening of X-ray peaks confirms the evolution of crystalline phases in the ZnO QDs. Quantitative analysis of size-dependent strain effects is performed through the Williamson-Hall model. The QD mean size estimated from FESEM and XRD displays high consistency. Room-temperature PL peaks of 3.37ev are attributed to the radiative recombination of electrons and holes from the ZnO QDs/Si interface.

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Great blue-shift of luminescence of ZnO nanoparticle array constructed from ZnO quantum dots

Cited by 49 publications

References 32 publications

Metastability effects on the photoluminescence of ZnO nano-micro structures grown at low temperature and influence of the precursors on their morphology and structure

Metastability effects on the photoluminescence of ZnO nano-micro structures grown at low temperature and influence of the precursors on their morphology and structure

Synthesis and Characterization of Nanocrystalline ZnO Doped with Al3+ and Ni2+ by a Sol–Gel Method Coupled with Ultrasound Irradiation

ZnO QDs Deposited on Si by Sol-Gel Method: Role of Annealing Temperature on Structural and Optical Properties

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