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- Aydin, C., et al.
(författare)
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Synthesis, diffused reflectance and electrical properties of nanocrystalline Fe-doped ZnO via sol-gel calcination technique
- 2013
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Ingår i: Optics and Laser Technology. - : Elsevier BV. - 0030-3992. ; 48, s. 447-452
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Tidskriftsartikel (refereegranskat)abstract
- The nanocrystalline ZnO:Fe semiconductor oxides were successfully synthesized via the sol-gel calcination method. Structural, optical and electrical properties of the investigated samples were characterized by various techniques such as atomic force microscopy (AFM), UV-vis absorption and electrical transport measurements. The optical band gap for undoped ZnO (3.19 eV) decreases (2.75 eV) with increasing Fe-doped ZnO (20%). The temperature dependences of the electrical conductivities of undoped ZnO and Fe-doped ZnO were measured and analyzed by Arrhenius equation. The electrical conductivity of the samples decreases with the increase of Fe doping ratio; hence, the electrical conductivity mechanism is controlled by thermally activated processes. To support the nanostructure of Fe-doped ZnO, AFM micrographs were performed. (C) 2012 Elsevier Ltd. All rights reserved.
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- Mahmmoud Sayed, Abd El-sadek, et al.
(författare)
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Electronic transport mechanism of CdTe nanocrystalline
- 2011
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Ingår i: Materials Chemistry and Physics. - : Elsevier BV. - 0254-0584. ; 130:1-2, s. 591-597
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Tidskriftsartikel (refereegranskat)abstract
- CdTe nanocrystalline powder was synthesized by chemical process. The structure of CdTe nanocrystalline was investigated by means of X-ray diffraction (XRD) technique, energy-dispersive X-ray analysis (EDAX) spectrum and transmission electron microscopy (TEM). The selected area electron diffraction (SAED) study confirms the crystallinity of the CdTe nanocrystalline. Some structural parameters such as the mean crystallite size, the dislocation density and the strain were calculated. The temperature dependence of the dc and ac conductivity was measured in the temperature range 293-423 K. It was found that the dc conductivity is thermally activated type. Values of dc activation energy and the pre-exponential were determined. The ac conductivity was found to increase with increasing both the temperature and frequency and follows the power low. The frequency exponent s was found to decrease with increasing temperature. The correlated barrier hopping (CBH) model was found to be applying to the ac conductivity data. The maximum barrier height W(m) and the density of localized states N(E(F)) were calculated and equal to 0.47 eV and 8.82 x 10(22) to 1.43 x10(23) eV(-1) cm(-3), respectively. CdTe nanomaterial is a good candidate for semiconductor devices due to its high conductivity. (C) 2011 Elsevier B.V. All rights reserved.
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- Yahia, I. S., et al.
(författare)
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Methyl orange (CI acid orange 52) as a new organic semiconductor: Conduction mechanism and dielectrical relaxation
- 2012
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Ingår i: Dyes and Pigments. - : Elsevier BV. - 1873-3743 .- 0143-7208. ; 93:1-3, s. 1434-1440
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Tidskriftsartikel (refereegranskat)abstract
- The structural, electrical and dielectrical properties of the methyl orange (MO) have been investigated by X-ray diffraction and thermal analysis methods. The electrical conduction and dielectrical relaxation mechanisms of the organic compound at various frequencies and temperatures were analyzed by impedance spectroscopy. The direct current (DC) electrical conductivity confirmed that methyl orange is an organic semiconductor with calculated electronic parameters. The alternating current (AC) electrical conductivity of the sample is controlled by the correlated barrier hopping (CBH) conduction mechanism. The values of the activation energy, the density of states and the binding energy for the alternating current mechanism were determined. The real and imaginary (Z' and Z '') parts of the impedance were found to be a frequency dependence. It was found that Cole-Cole plots of the sample confirm the existence of a temperature-dependent non-Debye relaxation mechanism. (C) 2011 Elsevier Ltd. All rights reserved.
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