Materials Literature
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Temperature-dependent reversal of the rectifying polarity has been observed in Au/TlGaSe2 Schottky junctions. To explain the experimental findings the important role of the tunneling current was taken into account. Besides, it was found that the temperature range, where the rectifying polarity reversal is observed, co…
In the framework of Landau–Devonshire thermodynamic theory, which is used in conventional ferroelectrics, we investigate the ferroelectric properties of the 1–3 type multiferroic BaTiO3–CoFe2O4 nanocomposite films. The films are epitaxial both in plane and out of plane with self-assembled hexagonal arrays of CoFe2O4 n…
Ba 0.7 Sr 0.3 TiO 3 (BST) thick films with thickness up to 1 μm were deposited on Pt-coated silicon substrates by ion beam sputtering, followed by an annealing treatment. It is demonstrated that pure well-crystallized perovskite phase could be obtained in thick BST films by a low temperature process (535 °C). The BST…
Polycrystalline SrBi2Ta2O9 (SBT) thin films were grown on Pt/Ti/SiO2/Si substrates by pulsed laser ablation technique. Phase analyses of the deposited films were studied by grazing incidence x-ray diffraction. Microstructural and interfaces of the SBT film were investigated using a field emission scanning electron mic…
In this work, we use ultrafast optical pump-optical probe spectroscopy to probe the polaron dynamics in La0.7Ca0.3MnO3 (LCMO) thin films. The temporal evolution in transient reflectivity change ΔR/R exhibits two relaxing components: a fast component with a time constant of subpicosecond and a slow component with time…
Using first-principles calculations based on density functional theory, N-codoped ZnO:Co has been demonstrated to be potentially a p-type diluted magnetic semiconductor. By investigating 13 geometrically distinct configurations, Co and N dopants are found to have a tendency toward staying close to each other with most…
Hydrogen storage in TiCr2 alloy of AB2 type with C15 Laves phase structure has been studied using density functional theory and plane-wave pseudopotential technique. The H atom interacts stronger with Cr atoms than with Ti and tends to occupy the g (2A2B) site due to the largest interstitial space. The g sites togethe…
An atmospheric pressure microplasma jet was employed as a deposition tool to fabricate silicon oxycarbide films from tetraethoxysilane-argon (Ar) mixture gas at room temperature. Resultant films exhibit intense visible emission under a 325 nm excitation which appears white to naked eyes in the range from ∼1.75 to ∼3.5…
( 1 − x ) PbTiO 3 – x Bi ( Zn 1 / 2 Ti 1 / 2 ) O 3 solid solutions show a much enhanced tetragonality (c/a) and Curie temperature (TC). The detailed structure of (1−x)PbTiO3–xBi(Zn1/2Ti1/2)O3 is studied by means of neutron powder diffraction based on the Rietveld refinement. Zn exhibits a more polarizable property tha…
Ultralow dielectric permittivity (k=2.58) nanohybrid dielectric film was obtained by dispersing 3.0 wt % mesoporous silicate (MCM-41) particles with nanosize hollow channels into polyimide (PI) polymer. The ultralow k value of the hybrid film can be mainly attributed to the low k value of MCM-41 itself and the small a…
( 100 ) -Ba 0.65 Sr 0.35 TiO 3 (BST) films were deposited on Pt/Ti/SiO2/Si substrates using a low-temperature self-buffered layer. X-ray diffraction and atomic force microscope investigations show that the microstructure of BST films strongly depends on surface morphology of annealed self-buffered layer. The mechanism…
First principles calculations are employed to investigate both type I and II silicon clathrates. The phonon and infrared spectra of both types of clathrate are obtained. We find a localized vibrational mode of Si46 whose frequency is 375.0 cm−1, where the vibration in the mode localizes in the hexagonal chain. The hea…
This paper reports on ab initio numerical simulations of the effect of Co and Cu dopings on the electronic structure and optical properties of ZnO, pursued to develop diluted magnetic semiconductors vitally needed for spintronic applications. The simulations are based upon the Perdew-Burke-Enzerh generalized gradient…
The degenerate-four-wave-mixing, ultrafast optical pump-probe reflection, and scattering techniques were applied to study the nonlinear optical properties of VO2 in insulating and metallic phases. The third-order nonlinear susceptibility was measured for thin films at different excitation regimes. The VO2 recovery dyn…
We investigate theoretically the Hartman effect in quantum tunneling through single and double barriers in a single graphene layer. The numerical results indicate that the Hartman effect in graphene depends heavily on the incident angle and the energy of the carrier in the tunneling process through single and double b…
The magnetic nature of Zn1−xCoxO dilute magnetic semiconductor (DMS) thin films grown by pulsed laser deposition is investigated by x-ray absorption fine structure spectroscopy and x-ray diffraction. We show that a single phase of the substitutional Co atoms occupied Zn sites in the ZnO matrix exists in the Zn0.98Co0.…
We report positron depth-profiling studies on the hydrogen sorption behavior and phase evolution of Mg-based thin films. We show that the main changes in the depth profiles resulting from the hydrogenation to the respective metal hydrides are related to a clear broadening in the observed electron momentum densities in…
We report electroluminescence (EL) of colloidal CdSe/CdS, CdSe/ZnS, and CdSe/CdS/CdZnS/ZnS core/shell quantum dots (QDs) in multilayer light-emitting diodes (LEDs) fabricated by spin coating a near monolayer of the core/shell QDs on cross-linkable hole transporting layers. It is found that CdSe/CdS QD-LEDs exhibit a f…
ZnO film, with urea as nitrogen source to dope its p-type, is deposited by pulsed laser on n-type (100) Si substrate to fabricate p-ZnO/n-Si heterojunctions. The current-voltage (I-V) characteristics of the heterojunction have been studied in the temperature range 140–300 K. The turn on voltage decreased with increasi…
We present a theoretical study on the radiative and nonradiative decay rates of an optical emitter in close proximity to a prolate-shaped metal nanoparticle. We use the model developed by Gersten and Nitzan [J. Chem. Phys. 75, 1139 (1981)] that we correct for radiative reaction and dynamic depolarization. Based on thi…