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Akhilesh K. Arora

Bio: Akhilesh K. Arora is an academic researcher. The author has contributed to research in topics: Dispersion (optics) & Phonon. The author has an hindex of 1, co-authored 1 publications receiving 414 citations.

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TL;DR: In this article, the authors investigated the effect of confinement on optical phonons of different symmetries in the nanoparticles of zinc oxide with wurtzite structure using Raman spectroscopy.
Abstract: Effect of confinement is investigated on optical phonons of different symmetries in the nanoparticles of zinc oxide with wurtzite structure using Raman spectroscopy. An optical phonon confinement model is used for calculating the theoretical line shapes, which exhibit different asymmetric broadening and shifts, depending on the symmetries of phonon and their dispersion curves. The best fit to the data is found for particle diameters consistent with those estimated using x-ray diffraction.

438 citations


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TL;DR: The semiconductor ZnO has gained substantial interest in the research community in part because of its large exciton binding energy (60meV) which could lead to lasing action based on exciton recombination even above room temperature.
Abstract: The semiconductor ZnO has gained substantial interest in the research community in part because of its large exciton binding energy (60meV) which could lead to lasing action based on exciton recombination even above room temperature. Even though research focusing on ZnO goes back many decades, the renewed interest is fueled by availability of high-quality substrates and reports of p-type conduction and ferromagnetic behavior when doped with transitions metals, both of which remain controversial. It is this renewed interest in ZnO which forms the basis of this review. As mentioned already, ZnO is not new to the semiconductor field, with studies of its lattice parameter dating back to 1935 by Bunn [Proc. Phys. Soc. London 47, 836 (1935)], studies of its vibrational properties with Raman scattering in 1966 by Damen et al. [Phys. Rev. 142, 570 (1966)], detailed optical studies in 1954 by Mollwo [Z. Angew. Phys. 6, 257 (1954)], and its growth by chemical-vapor transport in 1970 by Galli and Coker [Appl. Phys. ...

10,260 citations

Journal ArticleDOI
TL;DR: The ZnO with oxygen vacancies are found to be efficient for photodecomposition of 2,4-dichlorophenol under visible light irradiation and a narrowing bandgap can be confirmed by the enhancement of the photocurrent response when theZnO was irradiated with visible light.
Abstract: Oxygen vacancies in crystal have important impacts on the electronic properties of ZnO. With ZnO2 as precursors, we introduce a high concentration of oxygen vacancies into ZnO successfully. The obtained ZnO exhibits a yellow color, and the absorption edge shifts to longer wavelength. Raman and XPS spectra reveal that the concentration of oxygen vacancies in the ZnO decreased when the samples are annealed at higher temperature in air. It is consistent with the theory calculation. The increasing of oxygen vacancies results in a narrowing bandgap and increases the visible light absorption of the ZnO. The narrowing bandgap can be confirmed by the enhancement of the photocurrent response when the ZnO was irradiated with visible light. The ZnO with oxygen vacancies are found to be efficient for photodecomposition of 2,4-dichlorophenol under visible light irradiation.

1,213 citations

Journal ArticleDOI
TL;DR: In this article, a large quantity of nanosized ZnO tubular structures was prepared using a very simple thermal evaporation of mixed Zn-ZnO powders under a wet oxidation condition.
Abstract: A large quantity of nanosized ZnO tubular structures was prepared using a very simple thermal evaporation of mixed Zn–ZnO powders under a wet oxidation condition. The ZnO nanotubes have a hollow core with crystalline wall of 8–20 nm in thickness. Optical properties of ZnO nanotubes were studied at room temperature. Raman peaks arising from the ZnO nanotubes were analyzed, which correspond well to that of the bulk ZnO sample. The photoluminescence measurements of ZnO nanotubes revealed an intensive UV peak at 377 nm corresponding to the free exciton emission, and a broad peak at about 500 nm arising from defect-related emission.

604 citations

Journal ArticleDOI
TL;DR: In this article, the authors classify the nanostructures into (1) nanoparticles, which offer large surface area to photo-electrode film for dye-adsorption, (2) core-shell structures, which are derived from the nanoparticles however with a consideration to reduce charge recombination by forming a coating layer, (3) one-dimensional nanstructures such as nanowires and nanotubes, which provide direct pathways for electron transport much faster than in the nanoparticle films, and (4) three-dimensional nanoparticles such as Nan

603 citations