National Institute Of Materials Physics - Romania

Publications

5781 articles found

3531. Defects in silicon: From bulk crystals to nanostructures

Authors: Ciurea, ML; Iancu, V; Lazanu, S; Lepadatu, AM; Rusnac, E; Stavarache, I

Published: 2008, ROMANIAN REPORTS IN PHYSICS, 60, 748, DOI:

Defects in silicon are studied as function of the dimensionality of the investigated structures. Defects produced by strong irradiation in bulk crystals, like vacancies or interstitial defects, induce other defects, so that the irradiated devices are irreversibly damaged. Defects in nanostructures are shown to be produced mainly by surface/interface states and strains, and are therefore specific to the investigated structure. The modeling of the experimental methods allows the determination of defect parameters that are not directly measurable. The carriers capture on quantum confinement levels in OD systems has a similar behavior with the trapping phenomena.

3532. Sensitivity to Reducing Gases of Polymer-Iron Nanocomposite Materials

Authors: Tomescu, A; Simion, CE; Alexandrescu, R; Morjan, I; Scarisoreanu, M

Published: 2008, ROMANIAN JOURNAL OF INFORMATION SCIENCE AND TECHNOLOGY, 11, 95, DOI:

Electrical properties of new Polymer-Iron nanocomposite materials obtained by laser pyrolysis were investigated, in order to find applications for the detection of reducing gases. The aim of this paper was to prove the necessity of complex experimental investigation in order to point out the contribution of different types of adsorption. Usually resistance measurement cannot fully describe the surface interactions. The electronaffinity changes are of real interest for in-field conditions which always involve humidity of surrounding gas atmosphere. On the other hand, the nanocomposite materials can be a solution for specific gas-sensing properties.

3533. MICROWAVE COMPACT FILTERS USING MULTILAYER STRUCTURES

Authors: Militaru, N; Lojewski, G; Banciu, MG

Published: OCT-DEC 2008, REVUE ROUMAINE DES SCIENCES TECHNIQUES-SERIE ELECTROTECHNIQUE ET ENERGETIQUE, 53, 472, DOI:

This paper is dedicated mainly to the study of couplings between planar resonators in multilayer structures with modified (defected) ground plane. Couplings between two miniaturized resonators are investigated, by full electromagnetic field simulation. Based on the results of this study, several models of planar microwave bandpass filters, with a single or with two apertures, are designed, verified by simulation, fabricated and measured. Compared to the classical filters, these novel structures show a good compactness and can offer some technological advantages.

3534. ENERGY LOSS AND DAMAGE PRODUCTION BY HEAVY IONS AND STRANGE QUARK MATTER IN SILICON

Authors: Lazanu, S; Lazanu, I

Published: 2008, ASTROPARTICLE, PARTICLE AND SPACE PHYSICS, DETECTORS AND MEDICAL PHYSICS APPLICATIONS, 4, +, DOI: 10.1142/9789812819093_0082

In this contribution the peculiarities of the behaviour of strange quark matter in respect to ordinary ions in silicon are investigated, and a tentative to identify possible observable effects of degradation is made.

3535. Correlation of Structural and MW-MMW Dielectric Properties with Vibrational Modes in BaX1/3Ta2/3O3 Complex Perovskites

Authors: Toacsan, MI; Ioachim, A; Nedelcu, L; Banciu, MG; Mihut, L; Szilagyi, A

Published: 2008, 2008 33RD INTERNATIONAL CONFERENCE ON INFRARED, MILLIMETER AND TERAHERTZ WAVES, VOLS 1 AND 2, +, DOI:

Ceramic based Ba(Zn1/3Ta2/3)O-3 materials were prepared by solid-state reaction. Studies on microwave dielectric parameters in correlation with structural and Raman investigations were performed. Sintering temperatures higher than 1600 degrees C are required in order to obtain dielectric properties suitable for millimeter wave applications.

3536. EIS studies of electrodeposition process of manganese and copper doped ZnO wires

Authors: Sima, M; Enculescu, I; Sima, M; Vasile, E; Visan, T

Published: MAR-APR 2008, SURFACE AND INTERFACE ANALYSIS, 40, 565, DOI: 10.1002/sia.2721

Electrodeposition of manganese- and copper-doped ZnO wires into polycarbonate membranes, from an aqueous solution containing 0.05 mol dm(-3) Zn(NO3)(2)+ 0.01 mol dm(-3) Mn(NO3)(2)+ 0.0005 mol dm(-3) Cu(NO3)(2)+ 0.0075 mol dm(-3) lactic acid, pH = 4.7 was investigated using linear sweep voltammetry and electrochemical impedance spectroscopy (EIS). The equivalent electrical circuits for fitting experimental results were similar to those for characterization of metal/polymer coating systems. impedance data and voltarnmetric curves showed that an increase of local pH due to reduction process of nitrate ions induces the co-precipitations of metal ions in the proximity of electrode as oxides. Copyright (c) 2008 John Wiley & Sons, Ltd.

3537. A SOLID STATE NANO-GENERATOR: CONCEPT, DESIGN AND THEORETICAL ESTIMATIONS

Authors: Vopsaroiu, M; Cain, MG; Kuncser, V; Blackburn, J

Published: 2008, FUNCTIONALIZED NANOSCALE MATERIALS, DEVICES AND SYSTEMS, +, DOI: 10.1007/978-1-4020-8903-9_44

Nano-technology is a very attractive area of research and innovation because it allows the current trends in miniaturization to continue. The transition from micro scale to nano scale devices has already taken place in many applications such as electronics, magnetic recording and nano-biophysics. However, as we scale down the size of the structures and devices, it becomes obvious that the classical behavior will break down at the nano-scale and an interesting superposition of classical and quantum effects will emerge. Therefore, the validity of classical physics is questioned and many aspects of physics are now being revisited from the point of view of nano-technologies. In line with the new developments in miniaturization and nano-technologies, we propose in this letter a simple mechanism that applies the Faraday effect at the nano-scale in order to create a possible solid-state energy nano-generator device. The proposed nano-generator functionality is based oil what we shall call the Super-Paramagnetic Electromotive Force (SPEF) effect. This has the potential to produce a very small voltage on short time scales by converting directly thermal energy at room temperature to electromotive energy Without the need for external work or mechanical motion.

3538. Ab INITIO STUDY OF NEUTRAL OXYGEN VACANCIES IN RUTILE TiO2

Authors: Plugaru, R; Artigas, M; Plugaru, N

Published: 2008, CAS: 2008 INTERNATIONAL SEMICONDUCTOR CONFERENCE, PROCEEDINGS, +, DOI: 10.1109/SMICND.2008.4703393

We present results of ab initio. supercell calculations performed in the DFT-L(S)DA framework on rutile TiO2 phase with neutral oxygen vacancies (OVs), in the low defect concentration range (<= 6.25 at. %). The different OVs distributions in the supercell allow us to determine the localization and structure of the vacancy-induced states, the effect of vacancy concentration on the occupation numbers, as well as vacancy energetics. The present studs, benefits of the high accuracy in the total energy and band structure calculations of the full potential method utilized

3539. Radiation characteristics of a novel compact microstrip patch resonator

Authors: Militaru, N; Banciu, MG; Nedelcu, L; Lojewski, G

Published: 2008, ECCSC 08: 4TH EUROPEAN CONFERENCE ON CIRCUITS AND SYSTEMS FOR COMMUNICATIONS, +, DOI: 10.1109/ECCSC.2008.4611680

In this paper a new type of dual-mode compact resonator for mobile communication systems, in the 900 MHz frequency band, is investigated. This compact planar resonator, developed on a 0.635 mm substrate with a 10.8 dielectric constant, has a square shape with an edge of 20.5 mm. For this dual resonator, several methods of modes coupling were considered. The radiation characteristics of this new resonator were investigated.

3540. Combinatorial pulsed laser deposition of thin films

Authors: Craciun, V; Craciun, D; Mihailescu, IN; Socol, G; Stefan, N; Miroiu, M; Galca, AC; Bourne, G

Published: 2008, HIGH-POWER LASER ABLATION VII, PTS 1-2, 7005, DOI: 10.1117/12.782589

Pulsed Laser Deposition (PLD) is an ideal technique to be used for combinatorial approaches. By simply changing the deposition targets one can obtain alternating layers with different periodicities both vertically and laterally, along the substrate surface. By changing the laser impact area location and the number of pulses on each target used for ablation, one can grow films with a continuous variation of the chemical composition, which will be a function of the location on the substrate. To illustrate the advantages and versatility of this Combinatorial PLD (C-PLD) technique, several examples of films used in applications where more than one property should be tailored or optimized are presented. Investigations of thermo-chemical stability, chemical bonding and crystalline structure of thin films of mixtures of HfO2 and Al2O3 that are used as high-k dielectric layers in advanced C-MOS transistors is the first example, followed by a study of structural, mechanical, optical and electrical properties of mixtures of indium tin oxide and doped or pure zinc oxide that are used as transparent and conductive layers. The third example is from the deposition of multilayers of ZrC and ZrN with variable thicknesses to obtain hard coatings.