Transparent semiconductor zinc oxide thin films deposited on glass substrates by sol–gel process
TL;DR: In this paper, the influence of ZnO sols synthesized via different solvents (2-ME, EtOH or IPA) on the surface morphologies, microstructures, optical properties and resistivities of the obtained films were investigated.
About: This article is published in Ceramics International.The article was published on 2010-08-01. It has received 81 citations till now. The article focuses on the topics: Carbon film & Thin film.
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TL;DR: In this article, Tauc plots are fitted to a simple expression in which the intercept gives the band-gap and the fitting exponent identifies the electronic transition as direct or indirect (see Tauc et al., Phys. Status Solidi 15, 627 (1966); these are often called “Tauc” plots).
Abstract: One of the most frequently used methods for characterizing thin films is UV–Vis absorption. The near-edge region can be fitted to a simple expression in which the intercept gives the band-gap and the fitting exponent identifies the electronic transition as direct or indirect (see Tauc et al., Phys. Status Solidi 15, 627 (1966); these are often called “Tauc” plots). While the technique is powerful and simple, the accuracy of the fitted band-gap result is seldom stated or known. We tackle this question by refitting a large number of Tauc plots from the literature and look for trends. Nominally pure zinc oxide (ZnO) was chosen as a material with limited intrinsic deviation from stoichiometry and which has been widely studied. Our examination of the band gap values and their distribution leads to a discussion of some experimental factors that can bias the data and lead to either smaller or larger apparent values than would be expected. Finally, an easily evaluated figure-of-merit is defined that may help guide more accurate Tauc fitting. For samples with relatively sharper Tauc plot shapes, the population yields Eg(ZnO) as 3.276 ± 0.033 eV, in good agreement with data for single crystalline material.
765 citations
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TL;DR: The photocatalytic activity enhancement and reduced photocorrosion can be achieved because of increased surface area, enhanced hydrophilicity, and the interaction between the metal wire/ZnO and Ag/ ZnO heterostructure interface which can improve the charge separation of photogenerated charge carriers.
134 citations
Cites background from "Transparent semiconductor zinc oxid..."
...ZnO can be used for many applications, such as photocataysts [1], transparent conducting layer [2], photoconductor [3], and as sensors [4,5]....
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TL;DR: In this paper, the structural, compositional, electrical, and optical properties of the films were investigated using spin coating process using 0.2 M Zn 2 + precursor salt, monoethanolamine to Zn + ratio of 0.75, and 1 and 2 at.% aluminum as a dopant.
90 citations
TL;DR: In this article, low operation temperature NO 2 sensors can be achieved by growing the Ce-doped ZnO nanorods array films on the Al 2 O 3 substrates with Pt spiral electrodes.
88 citations
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TL;DR: In this article, the optical constants of amorphous Ge were determined for the photon energies from 0.08 to 1.6 eV, and the absorption is due to k-conserving transitions of holes between the valence bands as in p-type crystals.
Abstract: The optical constants of amorphous Ge are determined for the photon energies from 0.08 to 1.6 eV. From 0.08 to 0.5 eV, the absorption is due to k-conserving transitions of holes between the valence bands as in p-type crystals; the spin-orbit splitting is found to be 0.20 and 0.21 eV in non-annealed, and annealed samples respectively. The effective masses of the holes in the three bands are 0.49 m (respectively 0.43 m); 0.04 m, and 0.08 m. An absorption band is observed below the main absorption edge (at 300 °K the maximum of this band is at 0.86 eV); the absorption in this band increases with increasing temperature. This band is considered to be due to excitons bound to neutral acceptors, and these are presumably the same ones that play a decisive role in the transport properties and which are considered to be associated with vacancies. The absorption edge has the form: ω2ϵ2∼(hω−Eg)2 (Eg = 0.88 eV at 300 °K). This suggests that the optical transitions conserve energy but not k vector, and that the densities of states near the band extrema have the same energy-dependence as in crystalline Ge. A simple theory describing this situation is proposed, and comparison of it with the experimental results leads to an estimate of the localization of the conduction-band wavefunctions.
8,184 citations
TL;DR: ZnO has received much attention over the past few years because it has a wide range of properties that depend on doping, including a range of conductivity from metallic to insulating (including n-type and p-type conductivity), high transparency, piezoelectricity, widebandgap semiconductivity, room-temperature ferromagnetism, and huge magneto-optic and chemical-sensing effects.
1,828 citations