National Institute Of Materials Physics - Romania

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861 articles found

541. Effect of the morphology on the optical and electrical properties of TPyP thin films deposited by vacuum evaporation

Authors: Socol, M; Rasoga, O; Stanculescu, F; Girtan, M; Stanculescu, A

Published: DEC 2010, OPTOELECTRONICS AND ADVANCED MATERIALS-RAPID COMMUNICATIONS, 4, 2038, DOI:

We have studied the effect of the morphology on the optical and electrical properties of the TPyP thin films deposited by vacuum evaporation on different substrates (Si with different characteristics, ITO, quartz and glass). The presence of some well-defined B and Q absorption bands has been evidenced. FTIR and photoluminescence measurements have been used to confirm the preservation of the chemical structure of the compound during the evaporation process. The contact Au/TPyP/Si(n) is rectifier, while a blocking behavior has been shown by Si(n)/TPyP/Si(n) and ITO/TPyP/Si(n) and an injector dominated behavior by Si(p)/TPyP/Si(p) and ITO/TPyP/Si(p) heterostructures. The best transmission was obtained on TPyP film deposited on ITO and the highest value of the current in heterostructures Si(n) electrode characterised by a large grain morphology and in consequence by a weak optical and charge carrier scattering at the grain boundaries.

542. On the structural, morphological, optical and electrical properties of sol-gel deposited ZnO In films

Authors: Girtan, M; Socol, M; Pattier, B; Sylla, M; Stanculescu, A

Published: NOV 1 2010, THIN SOLID FILMS, 519, 577, DOI: 10.1016/j.tsf.2010.07.006

Indium-doped zinc oxide thin films deposition was performed by the sol-gel technique using homogeneous and stable solutions of zinc acetate 2-hydrate and indium chloride in ethanol Films were spin coated onto glass substrates After drying and after a heat treatment at 450 degrees C highly transparent (80%-90%) films were obtained The effect on the structural morphological optical and electrical thin films properties of the dopant concentration was investigated The temperature dependencies of the electrical conductivity under vacuum and in open atmosphere were analysed and discussed (C) 2010 Elsevier B V All rights reserved

543. SYNTHESIS AND LUMINESCENCE PROPERTIES OF Nd-DOPED CHALCOGENIDE GLASS (Ge5As2S13) (NdCl3) x (x=0.3%, 0.5%)

Authors: Georgescu, S; Voiculescu, AM; Salamu, S; Niciu, H; Niciu, D; Popescu, M; Lorinczi, A; Velea, A; Simandan, ID

Published: NOV 2010, CHALCOGENIDE LETTERS, 7, 624, DOI:

The synthesis of the chalcogenide glass (Ge5As2S13) doped by Nd3+ has been carried out. The bulk glass develops a small amount of Nd2O3 and As2O3 crystallites besides some amount of (NdCl3)*6H(2)O crystalline phase initially introduced during synthesis. The optical absorption spectra demonstrate the presence of the Nd3+ both in the amorphous phase and in crystalline combinations. The formation of Nd2O3 crystallites was explained by the reaction of water with neodymium chloride. The presence of As2O3 is due to the oxidation of As from the glass during preparation.

544. MAPLE preparation and characterization of benzil thin films

Authors: Socol, M; Socol, G; Rasoga, O; Stanculescu, F; Stanculescu, A; Mihailescu, I; Ionita, I; Preda, N; Enculescu, M; Antohe, S

Published: NOV 2010, OPTOELECTRONICS AND ADVANCED MATERIALS-RAPID COMMUNICATIONS, 4, 1806, DOI:

In this study the Matrix Assisted Pulsed Laser Evaporation (MAPLE) technique was used to prepare thin films from a low melting point (< 100 degrees C) organic compound (benzil). Optical properties of the films have been investigated by UV-VIS, FTIR and PL spectroscopy. Details about crystallinity were obtained by XRD measurements. FTIR spectra have confirmed the preservation of the chemical structure of the compound during the deposition process. SEM and AFM investigation have evidenced a topography of the MAPLE deposited films characterized by different grain size depending on the deposition conditions. Second harmonic generation measurements have revealed that the MAPLE deposited benzil films have preserved the optical nonliniar properties of the bulk crystalline benzil.

545. STRUCTURAL DETAILS OF THE Ag-As2S3 INTERFACE OBTAINED BY VACUUM THERMAL EVAPORATION FOLLOWED BY GREEN LASER IRRADIATION

Authors: Lorinczi, A; Velea, A; Matei, E; Simandan, ID; Popescu, M

Published: NOV 2010, CHALCOGENIDE LETTERS, 7, 612, DOI:

As2S3 on Ag heterostructures deposited onto microscope glass substrates have been prepared. The quality of the hetero-structures has been investigated by careful analysis of the scanning electron microscope pictures taken on the native cross-sections, produced after the vacuum deposition sequence and various green laser irradiation times. The As2S3 layer is not uniformly grown, but reveals a columnar-like structure and multi-scale aggregation.

546. MOULDING PROCEDURE FOR THE PREPARATION OF INFRARED GLASSY MICROLENSES AND PRISMS BASED ON ARSENIC SULPHIDE CHALCOGENIDE GLASS

Authors: Niciu, H; Popescu, M; Velea, A; Lorinczi, A; Manea, A; Niciu, D; Lazarescu, M

Published: NOV 2010, CHALCOGENIDE LETTERS, 7, 629, DOI:

A new procedure for the production of infrared lenses and prisms based on As(2)S(3) chalcogeniude glass has been devised. Infrared components are obtained with the size in the range 100-1500 micrometers. The procedure allows for getting various curvature radii of the micrometer lenses, ranging from planno-convex to spherical ones.

547. Investigations of the neodymium doped quartz glasses obtained by the hybrid sot-gel method

Authors: Niciu, H; Vasiliu, C; Manea, A; Radu, D; Secu, M; Onose, C; Ghervase, L; Niciu, D; Feraru, ID; Grigorescu, CEA

Published: OCT 2010, OPTOELECTRONICS AND ADVANCED MATERIALS-RAPID COMMUNICATIONS, 4, 1623, DOI:

Undoped and neodymium doped quartz glasses were obtained by the hybrid sol-gel method. The vitrification was performed in He atmosphere. The Nd(3+) characteristic absorption bands in the UV and VIS were put into evidence. Investigations in the NIR range revealed a small amount (86 ppm) of OH(-) in the vitreous matrix. FTIR and Raman spectra exhibit the SiO(2) glass characteristic vibrations and also the characteristic vibrations of Si-OH and Si-Cl bonds. The photoluminescence peaks at 640, 920 and 1080 nm belonging to the Nd(3+) doped quartz glass were evidenced.

548. Structure and Mossbauer measurements on SnSe2 bulk and thin films

Authors: Bibicu, I; Lorinczi, A; Velea, A; Sava, F; Popescu, M

Published: OCT 2010, OPTOELECTRONICS AND ADVANCED MATERIALS-RAPID COMMUNICATIONS, 4, 1571, DOI:

Thin films samples of SnSe2 deposited by PLD and PED have been prepared and studied by XRD and Mossbauer spectroscopy. The films are crystalline with a major phase of SnSe2 and minor phase of amorphous SnSe2. An oxidation process lead to the appearance of a thin layer of SnO2 on the surface of the PLD samples.

549. Optical and structural studies on Ba(Mg1/3Ta2/3)O-3 thin films obtained by radiofrequency assisted pulsed plasma deposition

Authors: Scarisoreanu, ND; Galca, AC; Nedelcu, L; Ioachim, A; Toacsan, MI; Morintale, E; Stoica, SD; Dinescu, M

Published: SEP 1 2010, APPLIED SURFACE SCIENCE, 256, 6530, DOI: 10.1016/j.apsusc.2010.04.041

Single-phase Ba(Mg1/3Ta2/3)O-3 thin films were prepared by radiofrequency plasma beam assisted pulsed laser deposition (RF-PLD) starting from a bulk ceramic target synthesized by solid state reaction. Atomic force microscopy, X-ray diffraction and spectroscopic ellipsometry were used for morphological, structural and optical characterization of the BMT thin films. The X-ray diffraction spectra show that the films exhibit a polycrystalline cubic structure. From spectroscopic ellipsometry analysis, the refractive index varies with the thin films deposition parameters. By using the transmission spectra and assuming a direct band to band transition a band gap value of approximate to 4.72 eV has been obtained. (C) 2010 Elsevier B.V. All rights reserved.

550. A new ZnO photoanode for dye-sensitized solar cell

Authors: Sima, M; Secu, M; Sima, M; Vasile, E

Published: SEP 2010, OPTOELECTRONICS AND ADVANCED MATERIALS-RAPID COMMUNICATIONS, 4, 1328, DOI:

The present work reports the preparation of nanostructured ZnO nanorods in a hydrothermal-electrochemical process and preliminary attempt to fabricate a dye-sensitized solar cell using this material as photoanode. Synthesis of ZnO nanorods in solutions with and without eosin Y dye, used as nanostructuring agent, was studied. ZnO nanorod arrays were characterized by photoluminescence spectroscopy, scanning electron microscopy and X-ray diffraction analysis. Fabricated dye-sensitized solar cell comprised a photoanode prepared with nanostructured ZnO nanorods and eosin Y dye, a platinum counter electrode and an electrolyte consisting of 0.5M KI + 0.03M I-2 in acetonitrile/ethylene carbonate (v/v=1/4). Performance parameters of dye-sensitized solar cell were extracted from standard current-voltage characteristic.