Author
Achintya Dhar
Bio: Achintya Dhar is an academic researcher from Indian Institute of Technology Kharagpur. The author has contributed to research in topics: Thin film & Sputter deposition. The author has an hindex of 22, co-authored 70 publications receiving 1129 citations.
Papers published on a yearly basis
Papers
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TL;DR: In this paper, the structural, electrical and optical properties of indium tin oxide (ITO) thin films have been investigated to obtain optimum values for resistivity, optical transmittance and surface smoothness.
Abstract: Indium tin oxide (ITO) thin films have been deposited by rf magnetron sputtering on glass substrates at different substrate temperatures. The structural, electrical and optical properties of these films have been investigated to obtain optimum values for resistivity, optical transmittance and surface smoothness. The film deposited at a substrate temperature of 300 °C shows good conductivity, optical transmittance, crystallinity and surface smoothness. These ITO films were used to fabricate organic light emitting diodes (OLEDs). The dc current–voltage (I–V) studies on ITO/PEDOT:PSS/MEH-PPV/Al test structures show better rectifying behaviour on a smoother ITO substrate.
92 citations
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TL;DR: Optically active strontium substituted barium titanate (Ba x Sr 1− x TiO 3 ) thin films have been prepared on p-silicon and glass (Corning 7059) substrates by RF magnetron sputtering in a flowing Ar/O 2 atmosphere as discussed by the authors.
69 citations
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TL;DR: In this article, X-ray diffraction and atomic force microscopy analyses were carried out on nanostructured ZnO thin films on Pyrex glass substrates and they were found to be transparent in the visible range above 400 nm, having transparency above 90%.
68 citations
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TL;DR: In this paper, a multilevel conductance switching in organic memory devices based on AlQ3 and Al/Al2O3 core-shell nanoparticles is demonstrated, and the effect of the Al layer thickness and the size of the nanoparticles on device performance is investigated.
Abstract: Multilevel conductance switching in organic memory devices based on AlQ3 and Al/Al2O3 core-shell nanoparticles is demonstrated. The effect of middle Al layer thickness and the size of the nanoparticles on device performance are investigated. The high-resolution transmission electron micrographs revealed the formation of core-shell nanoparticles. The device has shown a series of conductance states. These states are nonvolatile in nature and can be accessed by applying proper programming voltage above a threshold voltage. Field-induced transfer of charge carriers between AlQ3 and aluminum core is proposed to be responsible for conductance switching.
61 citations
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TL;DR: In this paper, the role of the thickness of the aluminum layer and the size of the nanoparticles in device performance was investigated, and the conductance switching was attributed to an electric field induced transfer of charge between aluminum nanoparticles and tris-(8-hydroxyquinoline)aluminum (AlQ3).
52 citations
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TL;DR: Nanocrystals (NCs) discussed in this Review are tiny crystals of metals, semiconductors, and magnetic material consisting of hundreds to a few thousand atoms each that are among the hottest research topics of the last decades.
Abstract: Nanocrystals (NCs) discussed in this Review are tiny crystals of metals, semiconductors, and magnetic material consisting of hundreds to a few thousand atoms each. Their size ranges from 2-3 to about 20 nm. What is special about this size regime that placed NCs among the hottest research topics of the last decades? The quantum mechanical coupling * To whom correspondence should be addressed. E-mail: dvtalapin@uchicago.edu. † The University of Chicago. ‡ Argonne National Lab. Chem. Rev. 2010, 110, 389–458 389
3,720 citations
16 Mar 1993
TL;DR: Giant and isotropic magnetoresistance as huge as −53% was observed in magnetic manganese oxide La0.72Ca0.25MnOz films with an intrinsic antiferromagnetic spin structure as discussed by the authors.
Abstract: Giant and isotropic magnetoresistance as huge as −53% was observed in magnetic manganese oxide La0.72Ca0.25MnOz films with an intrinsic antiferromagnetic spin structure. We ascribe this magnetoresistance to spin‐dependent electron scattering due to spin canting of the manganese oxide.
924 citations
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TL;DR: In this paper, a review of the state-of-the-art work on nanostructures of metal oxides is presented, focusing on the physical and chemical properties of low-dimensional oxide materials.
843 citations
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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: A comprehensive review of the literature on one-dimensional (1D) nanostructures (nanowires, nanoribbons, nanotubes, nanobelts, and nanofibers) of π-conjugated small molecules, oligomers, and polymers is presented in this article.
Abstract: This paper presents a comprehensive review of the literature on one-dimensional (1D) nanostructures (nanowires, nanoribbons, nanotubes, nanobelts, and nanofibers) of π-conjugated small molecules, oligomers, and polymers. The diverse methods used in assembling the molecular building blocks into 1D functional nanostructures and nanodevices are discussed, including hard and soft template-assisted synthesis, electrospinning, nanolithography, self-assembly in solution and at interfaces, physical vapor transport, and other strategies. Optical, charge transport, electronic, and photoconductive properties of nanowires and nanotubes of selected classes of π-conjugated molecular systems are discussed next, highlighting unique features of the 1D nanostructures compared to 2D thin films. Overview of applications of these 1D organic nanostructures ranging from nanoscale light-emitting diodes, field-emission devices, organic photovoltaics, sensors/biosensors, spin-electronics, and nanophotonics to nanoelectronics is th...
611 citations