National Institute Of Materials Physics - Romania

Publications

5781 articles found

3991. Swift heavy ion irradiation effects on doped alkali halides

Authors: Enculescu, M

Published: DEC 2005, JOURNAL OF OPTOELECTRONICS AND ADVANCED MATERIALS, 7, 3056, DOI:

The effects produced by heavy ion irradiation in KBr:Ag and KCl:Ag crystals are investigated using optical spectroscopy. For KCl, the results are compared with the effects obtained in the pure crystals. After irradiation with heavy ions up to 11.2 MeV/u specific energy, the absorption bands suffer a series of changes, related to the structure of defects and also to their dimensions. In the high Ag concentrated samples, the Ag+ ions are changing their valence to Ag- while in the samples containing Ag nanoclusters the irradiation induces changes in the nanocluster size.

3992. Growth of superconducting and non-superconducting whiskers in the Bi-Sr-Ca-Cu-O (BSCCO) system

Authors: Badica, P; Togano, K

Published: DEC 2005, JOURNAL OF MATERIALS RESEARCH, 20, 3367, DOI: 10.1557/JMR.2005.0413

Growth of such non-superconducting whiskers [Sr2.24Ca0.4Al2Ox, (Ca0.8-0.85Sr0.15-0.1)(2)CuO3, CuO, or Bi2.44Sr2Ca1.3-2Cu6.9-9.95Al0.35-0.46Ox (Cu-rich whiskers)] formed during the growth of Bi-2212 superconducting whiskers from powder or glassy substrates, is discussed. These whiskers are likely to grow from the bottom end, and there is a tight relationship with the growth of the Bi-2212 whiskers. A general reaction-path model for the whisker growth in the BSCCO system, independent of the type of the catalytic impurity and substrate, is proposed. When whiskers are grown under magnetic fields, up to 10 T, changes in the whisker size, aspect ratio, and morphology are observed.

3993. Coulomb scattering in nitride-based self-assembled quantum dot systems

Authors: Nielsen, TR; Gartner, P; Lorke, M; Seebeck, J; Jahnke, F

Published: DEC 2005, PHYSICAL REVIEW B, 72, DOI: 10.1103/PhysRevB.72.235311

We study the carrier capture and relaxation due to Coulomb scattering in group-III nitride quantum dots on the basis of population kinetics. For the states involved in the scattering processes the combined influence of the quantum-confined Stark effect and many-body renormalizations is taken into account. The charge separation induced by the built-in field has important consequences on the capture and relaxation rates. It is shown that its main effect comes through the renormalization of the energies of the states involved in the collisions and leads to an increase in the scattering efficency.

3994. Design and realisation of star-geometry dual-mode bandpass filter

Authors: Shen, S; Ramer, R

Published: NOV 28 2005, OPTICS EXPRESS, 13, 9757, DOI: 10.1364/OPEX.13.009753

A design of a planar dual-mode filter is proposed and developed for satellite and wireless communication systems. The novelty of the proposed structure consists of replacing simple diagonal design with a starlike one. This offers the ability of controlling the central frequency and the bandwidth. The filter was implemented on Rogers substrate with 10.8 dielectric constant. The proposed filter structure is 37% smaller in size in comparison with traditional dual mode filters. (c) 2005 Optical Society of America.

3995. Mossbauer study of LaNiSn and NdNiSn compounds and their deuterides

Authors: Palade, P; Principi, G; Spataru, T; Blaha, P; Schwarz, K; Kuncser, V; Lo Russo, S; Dal Toe, S; Yartys, VA

Published: NOV 2005, JOURNAL OF RADIOANALYTICAL AND NUCLEAR CHEMISTRY, 266, 556, DOI: 10.1007/s10967-005-0947-7

LaNiSn and NdNiSn compounds and their deuterides have been studied by variable temperature Sn-119 Mossbauer spectroscopy. The hyperfine parameters obtained experimentally are in good agreement with those derived from first principle calculations. The enlargement of quadrupole splitting observed for LaNiSn after deuteration confirms the lower symmetry of electron density around tin atoms indicated by the calculation of partial Sn-p density of states (DOS). Magnetic ordering is observed at low temperature in deuterided NdNiSn.

3996. Coherent anti-Stokes Raman scattering on single-walled carbon nanotubes and copper phthalocyanine thin films excited through surface plasmons

Authors: Baltog, I; Baibarac, M; Lefrant, S

Published: NOV 2005, JOURNAL OF OPTICS A-PURE AND APPLIED OPTICS, 7, 639, DOI: 10.1088/1464-4258/7/11/003

Experimental data indicating an anti-Stokes Raman emission, reminiscent of coherent anti-Stokes Raman scattering (CARS), that originates in a wave-mixing process between the incident laser light (omega(1)) and Stokes Raman light (omega(s)) generated by a surface enhanced Raman scattering (SERS) mechanism are reported. The variation of anti-Stokes SERS spectra of single-walled carbon nanotubes (SWNTs) and copper phthalocyanine (CuPc) as a function of the film thickness, laser excitation intensity and numerical aperture of the microscopic objective used for collecting the scattered light are presented as experimental arguments.

3997. Elimination and formation of electrically active defects in hydrogenated silicon particle detectors irradiated with electrons

Authors: Makarenko, LF; Korshunov, FP; Lastovski, SB; Kazuchits, NM; Rusetsky, MS; Fretwurst, E; Lindstrom, G; Moll, M; Pintilie, I; Zamiatin, NI

Published: OCT 21 2005, NUCLEAR INSTRUMENTS & METHODS IN PHYSICS RESEARCH SECTION A-ACCELERATORS SPECTROMETERS DETECTORS AND ASSOCIATED EQUIPMENT, 552, 81, DOI: 10.1016/j.nima.2005.06.010

The influence of preliminary treatment in hydrogen plasma on elimination of radiation defects and formation of thermal donors has been studied in detector structures made of standard float zone silicon. The detectors were irradiated with 3.5MeV electrons and annealed at temperatures of 50-350 degrees C. It has been found that preliminary hydrogenation at 300 degrees C leads to disappearance of divacancies and vacancy-oxygen complexes at lower annealing temperatures. The annealing of hydrogenated and irradiated crystals is accompanied by hydrogen redistribution and formation of hydrogen-related donors. (c) 2005 Elsevier B.V. All rights reserved.

3998. Recent advancements in the development of radiation hard semiconductor detectors for S-LHC

Authors: Fretwurst, E; Adey, J; Al-Ajili, A; Alfieri, G; Allport, PP; Artuso, M; Assouak, S; Avset, BS; Barabashi, L; Barcz, A; Bates, R; Biagi, SF; Bilei, GM; Bisello, D; Blue, A; Blumenau, A; Boisvert, V; Bolla, G; Bondarenko, G; Borchi, E; Borrello, L; Bortoletto, D; Boscardin, M; Bosisio, L; Bowcock, TJV; Brodbeck, TJ; Broz, J; Bruzzi, M; Brzozowski, A; Buda, M; Buhmann, P; Buttar, C; Campabadal, F; Campbell, D; Candelori, A; Casse, G; Cavallini, A; Charron, S; Chilingarov, A; Chren, D; Cindro, V; Collins, P; Coluccia, R; Contarato, D; Coutinho, J; Creanza, D; Cunningham, L; Dalla Betta, GF; Dawson, I; de Boer, W; De Palma, M; Demina, R; Dervan, P; Dittongo, S; Dolezal, Z; Dolgolenko, A; Eberlein, T; Eremin, V; Fall, C; Fasolo, F; Ferbel, T; Fizzotti, F; Fleta, C; Focardi, E; Forton, E; Garcia, C; Garcia-Navarro, JE; Gaubas, E; Genest, MH; Gill, KA; Giolo, K; Glaser, M; Goessling, C; Golovine, V; Sevilla, SG; Gorelov, I; Goss, J; Bates, AG; Gregoire, G; Gregori, P; Grigoriev, E; Grillo, AA; Groza, A; Guskov, J; Haddad, L; Harkonen, J; Hauler, F; Hoeferkamp, M; Honniger, F; Horazdovsky, T; Horisberger, R; Horn, M; Houdayer, A; Hourahine, B; Hughes, G; Ilyashenko, I; Irmscher, K; Ivanov, A; Jarasiunas, K; Johansen, KMH; Jones, BK; Jones, R; Joram, C; Jungermann, L; Kalinina, E; Kaminski, P; Karpenko, A; Karpov, A; Kazlauskiene, V; Kazukauskas, V; Khivrich, V; Khomenkov, V; Kierstead, J; Klaiber-Lodewigs, J; Klingenberg, R; Kodys, P; Kohout, Z; Korjenevski, S; Koski, M; Kozlowski, R; Kozodaev, M; Kramberger, G; Krasel, O; Kuznetsov, A; Kwan, S; Lagomarsino, S; Lassila-Perini, K; Lastovetsky, V; Latino, G; Lazanu, I; Lazanu, S; Lebedev, A; Lebel, C; Leinonen, K; Leroy, C; Li, Z; Lindstrom, G; Linhart, V; Litovchenko, P; Litovchenko, A; Giudice, AL; Lozano, M; Luczynski, Z; Luukka, P; Macchiolo, A; Makarenko, LF; Mandic, I; Manfredotti, C; Manna, N; Garcia, SM; Marunko, S; Mathieson, K; Melone, J; Menichelli, D; Messineo, A; Metcalfe, J; Miglio, S; Mikuz, M; Miyamoto, J; Moll, M; Monakhov, E; Moscatelli, F; Naoumov, D; Nossarzewska-Orlowska, E; Nysten, J; Olivero, P; Oshea, V; Palviainen, T; Paolini, C; Parkes, C; Pesseri, D; Pein, U; Pellegrini, G; Perera, L; Petasecca, M; Plemonte, C; Pignatel, GU; Pinho, N; Pintilie, I; Pintilie, L; Polivtsev, L; Polozov, P; Popa, A; Popule, J; Pospisil, S; Pozza, A; Radicci, V; Rafi, JM; Rando, R; Roeder, R; Rohe, T; Ronchin, S; Rott, C; Roy, A; Ruzin, A; Sadrozinski, HFW; Sakalauskas, S; Scaringella, M; Schiavulli, L; Schnetzer, S; Schumm, B; Sciortino, S; Scorzoni, A; Segneri, G; Seidel, S; Seiden, A; Sellberg, G; Sellin, P; Sentenac, D; Shipsey, I; Sicho, P; Sloan, T; Solar, M; Son, S; Sopko, B; Sopko, V; Spencer, N; Stahl, J; Stolze, D; Stone, R; Storasta, J; Strokan, N; Sudzius, M; Surma, B; Suvorov, A; Svensson, BG; Tipton, P; Tomasek, M; Tsvetkov, A; Tuominen, E; Tuovinen, E; Tuuva, T; Tylchin, M; Uebersee, H; Uher, J; Ullan, M; Vaitkus, JV; Velthuis, J; Verbitskaya, E; Vrba, V; Wagner, G; Wilhelm, I; Worm, S; Wright, V; Wunstorf, R; Yiuri, Y; Zabierowski, P; Zaluzhny, A; Zavrtanik, M; Zen, M; Zhukov, V; Zorzi, N

Published: OCT 21 2005, NUCLEAR INSTRUMENTS & METHODS IN PHYSICS RESEARCH SECTION A-ACCELERATORS SPECTROMETERS DETECTORS AND ASSOCIATED EQUIPMENT, 552, 19, DOI: 10.1016/j.nima.2005.05.039

The proposed luminosity upgrade of the Large Hadron Collider (S-LHC) at CERN will demand the innermost layers of the vertex detectors to sustain fluences of about 10(16) hadrons/cm(2). Due to the high multiplicity of tracks, the required spatial resolution and the extremely harsh radiation field new detector concepts and semiconductor materials have to be explored for a possible solution of this challenge. The CERN RD50 collaboration "Development of Radiation Hard Semiconductor Devices for Very High Luminosity Colliders" has started in 2002 an R&D program for the development of detector technologies that will fulfill the requirements of the S-LHC. Different strategies are followed by RD50 to improve the radiation tolerance. These include the development of defect engineered silicon like Czochralski, epitaxial and oxygen-enriched silicon and of other semiconductor materials like SiC and GaN as well as extensive studies of the microscopic defects responsible for the degradation of irradiated sensors. Further, with 3D, Semi-3D and thin devices new detector concepts have been evaluated. These and other recent advancements of the RD50 collaboration are presented and discussed. (c) 2005 Elsevier B.V. All rights reserved.

3999. Radiation-induced donor generation in epitaxial and Cz diodes

Authors: Pintilie, I; Buda, M; Fretwurst, E; Honniger, F; Lindstrom, G; Stahl, J

Published: OCT 21 2005, NUCLEAR INSTRUMENTS & METHODS IN PHYSICS RESEARCH SECTION A-ACCELERATORS SPECTROMETERS DETECTORS AND ASSOCIATED EQUIPMENT, 552, 60, DOI: 10.1016/j.nima.2005.06.006

Thin epitaxial layers grown on Cz substrates (Epi) and high resistivity Cz diodes have been irradiated with fluences of 2 x 10(14) cm(-2) 24 GeV protons. It is shown that the differences in the changes observed in the effective doping concentration (N-eff) after irradiation of Epi silicon can be explained by the balance between the formation of two type of defects-a deep acceptor (the I center) and a shallow donor (the BD complex). The BD concentration in Epi material is evaluated to be similar to 1.3 x 10(12) cm(-3). (c) 2005 Elsevier B.V. All rights reserved.

4000. Characterization of oxygen dimer-enriched silicon detectors

Authors: Boisvert, V; Lindstrom, JL; Moll, M; Murin, LI; Pintilie, I

Published: OCT 21 2005, NUCLEAR INSTRUMENTS & METHODS IN PHYSICS RESEARCH SECTION A-ACCELERATORS SPECTROMETERS DETECTORS AND ASSOCIATED EQUIPMENT, 552, 55, DOI: 10.1016/j.nima.2005.06.005

Various types of silicon material and silicon p(+)n diodes have been treated to increase the concentration of the oxygen dimer (02) defect. This was done by exposing the bulk material and the diodes to 6 MeV electrons at a temperature of about 350 degrees C. FTIR spectroscopy has been performed on the processed material confirming the formation of oxygen dimer defects in Czochralski silicon pieces. We also show results from TSC characterization on processed diodes. Finally, we investigated the influence of the dimer enrichment process on the depletion voltage of silicon diodes and performed 24 GeV/c proton irradiations to study the evolution of the macroscopic diode characteristics as a function of fluence. (c) 2005 Elsevier B.V. All rights reserved.