Blueshift of optical band gap in ZnO thin films grown by metal-organic chemical-vapor deposition

Tan, Swee Tiam; Chen, B. J.; Sun, Xiao Wei; Fan, Wenhui; Kwok, Hoi Sing; Zhang, X. H.; Chua, Soo-Jin

doi:10.1063/1.1940137

Cited by 664 publications

(237 citation statements)

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“…As amorphous ZnO phase increases in the films grown at increasing withdrawal speed, the extended localization in the conduction and valence bands increases. In consequence, the absorption of photon is governed by amorphous ZnO, hence, the absorption edge is blue shifted [17]. The band gap is dependent on film thickness.…”

Section: Optical Propertiesmentioning

confidence: 99%

Fabrication and properties of zinc oxide thin film prepared by sol-gel dip coating method

Kayani

Iqbal

Riaz

et al. 2015

Materials Science-Poland

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ZnO thin films were deposited on a glass substrate by dip coating technique using a solution of zinc acetate, ethanol and distilled water. Optical constants, such as refractive index n and extinction coefficient k, were determined from transmittance spectrum in the ultraviolet-visible-near infrared (UV-Vis-NIR) regions using envelope methods. The films were found to exhibit high transmittance, low absorbance and low reflectance in the visible regions. Absorption coefficient ∝, and the thickness of the film t were calculated from interference of transmittance spectra. The direct optical band gap of the films was in the range of 3.98 to 3.54 eV and the thickness of the films was evaluated in the range of 173 to 323 nm, while the refractive index slightly varied in the range of 1.515 to 1.622 with an increase in withdrawal speed from 100 to 250 mm/s. The crystallographic structure of the films was analyzed with X-ray diffractometer. The films were amorphous in nature.

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Section: Optical Propertiesmentioning

confidence: 99%

Fabrication and properties of zinc oxide thin film prepared by sol-gel dip coating method

Kayani

Iqbal

Riaz

et al. 2015

Materials Science-Poland

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“…It means that the modification of the optical band gap in our samples cannot be explained by strain and dislocation density. In general, the amorphous phase has a larger optical band gap than the polycrystalline phase for the same material [42,43]. It can be seen from the Fig.…”

Section: Resultsmentioning

confidence: 83%

Preparation and characterization of dye-sensitized TiO2 nanorod solar cells

Chen

et al. 2015

Thin Solid Films

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TiO 2 nanorods were prepared by DC reactive magnetron sputtering technique and applied to dye-sensitized solar cells (DSSCs). The length of the TiO 2 nanorods was varied from 1 μm to 6 μm. The scanning electron microscopy images show that the nanorods are perpendicular to the substrate. Both the X-ray diffraction patterns and Raman scattering results show that the nanorods have an anatase phase; no other phase has been observed. (101) and the (220) diffraction peaks have been observed for the TiO 2 nanorods. The (101) diffraction peak intensity remained constant despite the increase of nanorod length, while the intensity of the (220) diffraction peak increased almost linearly with the nanorod length. These nanorods were used as the working electrodes in DSSCs and the effect of the nanorod length on the conversion efficiency has been studied. An optimum photoelectric conversion efficiency of 4.8% has been achieved for 4 μm length nanorods.

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“…Usually, excess carriers donated by impurities (blue shift of optical band-to-band transitions) lead to Burstein-Moss (BM) effect [24]. The laser ablation of Zn film by lowering laser power creates nanocrystalline or amorphous phase of ZnO [25]. This amorphous phase of ZnO is responsible for a blue shift in absorption spectra.…”

Section: Resultsmentioning

confidence: 99%

Optical emission and absorption spectra of Zn–ZnO core-shell nanostructures

Ghosh

Choudhary

2010

Journal of Experimental Nanoscience

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The core-shell Zn-ZnO nanostructures were fabricated from Zn-powder embedded in graphite (i.e. carbon matrix) in a thin-films form by an inexpensive vacuum arc technique followed by laser ablation. The grazing incidence X-ray diffraction pattern shows that intensity of Zn-peak decreases, and subtle ZnOpeak increasing with the increase in laser power. The high resolution transmission electron microscopic study clearly exhibits the formation of a core-shell nanostructure as fabricated by laser ablation. The emission characteristics of laser ablated (with different powers) samples show a strong exciton peak at 388 nm, and a few more weak peaks (due to weak defect states in the visible range). The optical absorption spectra were obtained from the excitonic peaks (from 344 nm to 317 nm) on decreasing laser power. These peaks occur due to the coupling of exciton absorption (from ZnO shell layer) and core metal interband absorption. The Zn-ZnO core-shell nanostructure is useful for nanophotonic applications.

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Blueshift of optical band gap in ZnO thin films grown by metal-organic chemical-vapor deposition

Cited by 664 publications

References 20 publications

Fabrication and properties of zinc oxide thin film prepared by sol-gel dip coating method

Fabrication and properties of zinc oxide thin film prepared by sol-gel dip coating method

Preparation and characterization of dye-sensitized TiO2 nanorod solar cells

Optical emission and absorption spectra of Zn–ZnO core-shell nanostructures

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