[en] Indium tin oxide thin films were deposited at room temperature on glass substrates by RF magnetron sputtering. The structural, electrical and optical properties of the films showed a dependence on target to substrate spacing and annealing temperature. Films deposited with a target to substrate spacing of 4 cm showed the lowest resistivity of 3.07x10^-3 Ω cm and maximum band gap of 3.89 eV on annealing at a temperature of 250 deg. C under high vacuum for 1 h

[en] The effect of halides on the electroluminescence spectra of ZnS:Pr is reported. Thin film electroluminescence (TFEL) devices having low threshold voltage and white light emission are prepared employing ZnS:PrF₃ as active layer and Sm₂O₃ as insulator in the MIS structure SnO₂-ZnS:Pr-Sm₂O₃-Al. The effect of F^-, Cl^-, Br^-, and O₂^- co-activation of ZnS:Pr TFEL devices on the EL emission spectra and brightness is investigated. The present device can be driven by much lower voltages without loss of brightness than conventional type devices

[en] The ac and dc conduction mechanism of vacuum evaporated Eu₂O₃ films deposited by an electron beam gun onto glass substrate are reported. The capacitance was measured over a frequency range from 1kHz to 1 MHz in the temperature range of 300 to 543 K. The dc current-voltage characteristics and breakdown voltage were measured as functions of temperature and film thickness. The ac conductance as a function of frequency and temperature is plotted and discussed

[en] A new ceramic insulator-superconductor composite Ba₂YNbO₆-YBa₂Cu₃O_7-δ is prepared and its normal state and superconducting state percolation properties are studied. The percolation threshold value is found to be around 17 vol% YBa₂Cu₃O₇, which agrees with the expected value for an ideal composite system. The critical exponent t describing the transport properties of the system also agrees with the expected value, but the value of the exponent u deviates from the expected value. The studies on this insulator-superconductor composite system show that the superconductor YBa₂Cu₃O₇ does not react with the insulator Ba₂YNbO₆ even at elevated temperature of 1000 C. Scanning electron microscopic studies shows a sharp boundary between YBa₂Cu₃O₇ and Ba₂YNbO₂ grains with no sign of interaction or interdiffusion. The implications of the non-reactivity has been discussed from a technological point of view. (orig.)

[en] Barium stannate is a wide band gap semiconductor with cubic perovskite structure. Polycrystalline bulk samples of BaSn_1−xFe_xO_3d (BFS), with x = 0.00, 0.02, 0.03, 0.05 and 0.10 were prepared by solid-state reaction. In this paper, we report the growth of undoped and Fe doped barium stannate thin films on fused silica substrate using pulsed laser deposition (PLD) technique at a relatively high substrate temperature and low oxygen pressure. The deposited films have wide bandgap and are transparent in the visible region. The X-ray diffraction analysis of the films confirmed the cubic structure. Microstructural studies were carried out using micro-Raman spectroscopy and AFM analysis. Defect induced Raman shifts were observed in the samples. Magnetic studies revealed an increase in magnetic properties for films doped with 10 at% Fe doped samples.

[en] Transparent thin films of amorphous zinc indium tin oxide were prepared at room temperature by co-sputtering of zinc oxide and indium tin oxide. Effect of oxygen partial pressure on the optical and electrical properties of amorphous zinc indium tin oxide thin films were investigated. Conductivity, carrier concentration and Hall mobility showed strong dependence on the oxygen partial pressure and these parameters decreased with the increase of oxygen pressure. The effect of subgap states caused a sharp difference in measured optical band gap values between the films deposited with and without oxygen partial pressure. Carrier transport studies were carried out by temperature dependent conductivity measurements. At low electron density, the conductivity showed thermally activated behaviour and at higher carrier concentrations it changed to almost degenerate band conduction. (copyright 2008 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim) (orig.)

[en] Eu-doped ZnO nanoparticles were synthesized by hydrothermal method. The Eu-dopant concentration has been varied by varying the amount of Eu-dopant concentration. These nanoparticles were structurally characterized by X-ray diffraction, transmission electron microscopy and selected area electron diffraction and it confirms the formation of nanoparticles having standard wurtzite structure. Photo-luminescence studies show that these nanoparticles exhibit a sharp red luminescence due to the intra-4f transitions of Eu³⁺ ions at an excitation of 397 nm and 466 nm. Luminescence quenching is observed in the nanoparticles as the Eu-dopant concentration increases. Incorporation of Eu in the nanoparticles was confirmed by the energy dispersive X-ray studies. (author)

[en] Full text: High k dielectrics has been extensively studied in the past few years for the applications such as gate oxide in thin film transistors, capacitor dielectrics, electrostrictive materials and tunable microwave devices. Dielectric materials like BST, PZT etc in their ferroelectric phase are commonly used for these applications because of their large inherent dielectric constant. But dielectric materials in its ferroelectric phase with its intrinsic hysteresis generally shows a high dielectric loss and they suffer from high leakage current. Rapid development in these area demands dielectric materials with large dielectric constant and tunability together with low dielectric loss. Paraelectric materials with a high dielectric constant and comparatively low dielectric loss are preferred for these type of applications. In the last few years various Bi based pyrochlore structures with general formula A₂B₂O₇ has attracted much scientific interest because of their reasonably high dielectric constant (80 to 200) low dielectric loss and large dielectric tunability. Dielectric - metal composite thin films have been found to improve the dielectric properties of the thin films. In the present study we have prepared AgBi_1.5Zn₁Nb_1.5O₇ (Ag-BZN) composite thin film by pulsed laser deposition. As the volume fraction of metals in these composites increase, the dielectric constant and conductivity increase gradually and when the volume fraction of the conductive powder reaches a critical value, the conductivity as well as dielectric constant of the composite increase by several orders of magnitude. The dependence of temperature and oxygen partial pressure on the structural, optical, and electrical properties of the Ag-BZN thin films were studied. The surface morphology and composition were analyzed by AFM and EDX measurements. The dielectric measurements on the thin films were carried out using impedance analyser in the Metal-Insulator-Metal (MIM) structure with Pt as the bottom electrode and Ti/Au as the top electrode. It is found that with low silver content in the film, the dielectric constant of the films has been increased more than 60 times, the leakage current has been reduced by 4 orders, the tunability has been increased up to 80% and FOM factor has been increased by more than 10 times. It makes Ag-BZN composite thin films, a promising material for tunable device applications as well as high k dielectric capacitor applications. (author)

[en] Indium tin oxide (ITO) thin films were deposited on glass substrates by RF magnetron sputtering. The influence of substrate temperature on the structural, electrical and optical properties was investigated. With increase in substrate temperature, the crystallinity of the films increased. The films exhibited (111) and (100) preferred orientations. All the films showed high transmittance (>85%) in the visible region. The band gap of the films increased with increase in substrate temperature. Films deposited with a substrate temperature of 150 degC showed the lowest resistivity of 2.1 x 10^-3 Ωcm and highest mobility of 17.8 cm²V^-1s^-1. (author)

[en] The radio frequency plasma generated during the sputtering of Indium Tin Oxide target using Argon was analyzed by Langmuir probe and optical-emission spectroscopy. The basic plasma parameters such as electron temperature and ion density were evaluated. These studies were carried out by varying the RF power from 20 to 50 W. A linear increase in ion density and an exponential decrease in electron temperature with rf power were observed. The measured plasma parameters were then correlated with the properties of ITO thin films deposited under similar plasma conditions