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1

Digitale Medien

Transition from relaxed to derelaxed amorphous silicon: Optical characterization (1993)

Reitano, R. ; Grimaldi, M. G. ; Baeri, P. ; [weitere]

[S.l.] : American Institute of Physics (AIP)

Journal of Applied Physics 74 (1993), S. 2850-2855

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ISSN: 1089-7550

Quelle: AIP Digital Archive

Thema: Physik

Notizen: Optical constants of relaxed, derelaxed, and partially relaxed amorphous silicon (a-Si) in the range 0.4–0.9 μm are reported. The thermodynamical state of amorphous silicon (a-Si) has been changed either by thermal treatments or low dose ion implantation. Ellipsometry has been used to evaluate the complex refractive index for several amorphous states with enthalpy content between that of the fully relaxed and fully derelaxed a-Si. We observed a strong correlation between the electronic structure as probed by our optical measurements and the topological short-range order as probed by Raman scattering.

Materialart: Digitale Medien

URL: http://dx.doi.org/10.1063/1.354637

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2

Digitale Medien

In situ and ex situ structural characterization of β-FeSi2 films epitaxially grown on Si(111) (1992)

Lagomarsino, S. ; Scarinci, F. ; Savelli, G. ; [weitere]

[S.l.] : American Institute of Physics (AIP)

Journal of Applied Physics 71 (1992), S. 1224-1228

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ISSN: 1089-7550

Quelle: AIP Digital Archive

Thema: Physik

Notizen: The structural properties of β-FeSi2 films grown on Si(111) are studied by means of several techniques. The films were grown in ultrahigh vacuum by solid phase epitaxy. The as-deposited Fe films were studied in situ by low energy electron diffraction (LEED) and Auger spectroscopy. Fe thicknesses were calibrated by Rutherford backscattering. The behavior of the FeMVV/SiLVV Auger peaks ratio intensity as a function of Fe thickness indicates a Stranski–Krastanov mode of growth. Annealing of the Fe layers at temperatures between 400 and 600 °C led to the β-FeSi2 formation. Sharp LEED patterns typical of the β-FeSi2 orthorhombic structure were obtained. X-ray double-crystal diffraction was carried out on a film about 200 A(ring) thick in order to determine the lattice mismatch between the β-FeSi2 and the Si(111) planes accurately. The measured value of (2.1±0.1)×10−2 unambiguously indicates that (101) epitaxy takes place only on Si(111). No elastic strain of the overlayer was evident. The full width at half maximum of the overlayer diffraction peak indicates a good crystalline quality. An upper limit for mosaic spread was determined to be about 0.05°.

Materialart: Digitale Medien

URL: http://dx.doi.org/10.1063/1.351292

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3

Digitale Medien

Dihydropyridine Modulation of Voltage-Activated Calcium Channels in PC12 Cells: Effect of Pertussis Toxin Pretreatment (1991)

Schettini, G. ; Meucci, O. ; Grimaldi, M. ; [weitere]

Oxford, UK : Blackwell Publishing Ltd

Journal of neurochemistry 56 (1991), S. 0

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ISSN: 1471-4159

Quelle: Blackwell Publishing Journal Backfiles 1879-2005

Thema: Medizin

Notizen: Abstract: In this study, we report the effect of pertussis toxin pretreatment on dihydropyridine modulation of voltage-sensitive calcium channels in PC12 cells. The rise in intracellular calcium concentration caused by potassium depolarization is not affected significantly by pertussis toxin pretreatment. Nicardipine, a dihydropyridine derivative, added either before or after potassium-induced depolarization, reduces the resultant elevation in cytosolic calcium level both in control and in pertussis toxin-treated cells. The dihydropyridine agonist Bay K 8644, when added before potassium, is able to enhance the potassium-induced spike of cytosolic calcium levels, an effect significantly reduced by pertussis toxin pretreatment. Moreover, the addition of Bay K 8644 after potassium holds the intracellular calcium concentration at a cytosolic sustained level during the slow inactivating phase of depolarization. This effect of Bay K 8644 is inhibited by nicardipine. Pertussis toxin pretreatment slightly weakens the effect of Bay K 8644 when added after potassium-induced depolarization, whereas it significantly reduces the nicardipine inhibition of cytosolic calcium rise stimulated by potassium and Bay K 8644, but not by potassium alone. In conclusion, our findings suggest that a pertussis toxin-sensitive guanine nucleotide regulatory protein could be involved in the interaction between dihydropyridine derivatives and voltage-dependent calcium channels.

Materialart: Digitale Medien

URL: http://dx.doi.org/10.1111/j.1471-4159.1991.tb01995.x

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4

Digitale Medien

Amorphization and defect recombination in ion implanted silicon carbide (1997)

Grimaldi, M. G. ; Calcagno, L. ; Musumeci, P.

[S.l.] : American Institute of Physics (AIP)

Journal of Applied Physics 81 (1997), S. 7181-7185

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ISSN: 1089-7550

Quelle: AIP Digital Archive

Thema: Physik

Notizen: The damage produced in silicon carbide single crystals by ion implantation was investigated by Rutherford backscattering channeling and transmission electron microscopy techniques. Implantations were performed at liquid nitrogen and at room temperatures with several ions to examine the effect of the ion mass and of the substrate temperature on the damaging process. The damage accumulation is approximately linear with fluence until amorphization occurs when the elastic energy density deposited by the ions overcomes a critical value. The critical energy density for amorphization depends on the substrate temperature and is greatest at 300 K indicating that defects recombination occurs already at room temperature. Formation of extended defects never occurred and point defects and uncollapsed clusters of point defects were found before amorphization even in the case of light ion implantation. The atomic displacement energy has been estimated to be ∼12 eV/atom from the analysis of the damage process in dilute collision cascades. © 1997 American Institute of Physics.

Materialart: Digitale Medien

URL: http://dx.doi.org/10.1063/1.365317

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5

Digitale Medien

Inhomogeneous pulsed laser melting of high-dose Ge-implanted silicon (1994)

Calcagnile, L. ; Grimaldi, M. G. ; Baeri, P.

[S.l.] : American Institute of Physics (AIP)

Journal of Applied Physics 76 (1994), S. 1833-1839

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ISSN: 1089-7550

Quelle: AIP Digital Archive

Thema: Physik

Notizen: Pulsed laser melting of Si substrates implanted either with 74Ge+ ions at a nominal dose of 1017 cm−2 or 28Si+ ions at a dose of 1016 cm−2 has been investigated by time-resolved reflectivity using visible and infrared probe laser beams. In Si-implanted samples one reflectivity peak is observed during irradiation with 25 ns ruby laser pulses due to the formation and solidification of a liquid layer nucleated at the sample surface. Instead, Ge-implanted Si samples show different reflectivity spectra during irradiation in the same experimental conditions. Two reflectivity peaks have been observed in Ge-implanted samples for laser energy densities below 0.5 J/cm2 whose origin cannot be explained with the same melting dynamics as in pure Si samples. The results are explained assuming that during laser irradiation an inhomogeneous melting process occurs in Ge-implanted samples. On the basis of time-resolved reflectivity, electron microscopy, and Rutherford backscattering measurements, a melting model is suggested for the melting process of Ge-implanted samples. According to this model the liquid phase is nucleated just below the sample surface because of the reduced melting temperature caused by the Gaussian Ge implantation profile. The two reflectivity peaks originate from a time modulation of the liquid-solid ratio at the sample surface.

Materialart: Digitale Medien

URL: http://dx.doi.org/10.1063/1.357703

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6

Digitale Medien

Pulsed laser heating measurement of relaxation-induced melting point increase in amorphous Si (1990)

Grimaldi, M. G. ; Baeri, P.

Woodbury, NY : American Institute of Physics (AIP)

Applied Physics Letters 57 (1990), S. 614-617

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ISSN: 1077-3118

Quelle: AIP Digital Archive

Thema: Physik

Notizen: The difference in the melting temperature of unrelaxed and relaxed amorphous silicon has been determined by measuring the energy density threshold for surface melting during nanosecond laser irradiation (λ=347 nm). The melting onset was detected by time-resolved reflectivity technique. Using particular samples in which a surface unrelaxed layer was generated by reimplanting a 400-nm-thick relaxed amorphous Si (a-Si) the difference in the melting temperature has been determined independently of the thermal properties of the a-Si. The melting temperature of relaxed a-Si resulted to be only 3.9% higher than that of unrelaxed a-Si, while on the basis of calorimetric data an ∼14% difference was expected. The reasons for this discrepancy are discussed. In addition a 24% increase in the product of thermal conductivity and specific heat of a-Si upon relaxation has been found.

Materialart: Digitale Medien

URL: http://dx.doi.org/10.1063/1.103614

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7

Digitale Medien

Reply to "Comment on ‘Amorphization and defect recombination in ion implanted silicon carbide' " [J. Appl. Phys. 83, 3935 (1998)] (1998)

Grimaldi, M. G. ; Calcagno, L.

[S.l.] : American Institute of Physics (AIP)

Journal of Applied Physics 83 (1998), S. 3937-3937

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ISSN: 1089-7550

Quelle: AIP Digital Archive

Thema: Physik

Notizen: The arguments supporting our determination of the atomic displacement energy in SiC by channeling analysis of the damage produced by a 30 keV He beam implanted at low temperature are discussed. © 1998 American Institute of Physics.

Materialart: Digitale Medien

URL: http://dx.doi.org/10.1063/1.367315

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8

Digitale Medien

Evidence of interfacial melting during pulsed laser irradiation of Ni2Si on Si (1987)

Grimaldi, M. G. ; Priolo, F. ; Baeri, P. ; [weitere]

Woodbury, NY : American Institute of Physics (AIP)

Applied Physics Letters 51 (1987), S. 649-651

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ISSN: 1077-3118

Quelle: AIP Digital Archive

Thema: Physik

Notizen: Interfacial melting of thin (∼65 nm) Ni2Si films thermally grown on 〈111〉 Si has been observed after pulsed laser irradiation. Low-energy implanted Bi was used as a marker to detect surface melting. Rutherford backscattering spectrometry has shown that the energy density threshold for interfacial mixing was lower than the one at which changes in the Bi profile occurred. Cross-section transmission electron microscopy performed on those samples has shown the existence of a reacted layer, ∼20 nm, at the silicide/silicon interface while no change in the structure of the outermost 50 nm was observed. The reacted layer formed sharp interfaces with both the underlying silicon and the silicide. Interfacial melting has been related to the presence in the phase diagram of an eutectic between the compound and the pure silicon.

Materialart: Digitale Medien

URL: http://dx.doi.org/10.1063/1.98344

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9

Digitale Medien

Damage induced by laser irradiation of NiSi2/Si 〈111〉 structures (1987)

Priolo, F. ; Grimaldi, M. G. ; Baeri, P. ; [weitere]

[S.l.] : American Institute of Physics (AIP)

Journal of Applied Physics 61 (1987), S. 2522-2526

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ISSN: 1089-7550

Quelle: AIP Digital Archive

Thema: Physik

Notizen: Thermally grown NiSi2 layers on 〈111〉 Si substrates were irradiated with single pulses of a Q-switched Nd laser. Melting and solidification dynamics, orientation and structure of the irradiated layers were investigated by in situ time-resolved reflectivity, Rutherford backscattering in combination with channeling and scanning electron microscopy. Melt starts from the surface at 0.35 J/cm2. When the energy density is enough to melt the entire layer, the epitaxially solidified NiSi2 is mainly of B-type orientation. The thermally grown or partially melted layers are a mixture of A- and B-type crystals. A substantial decrease in the reflectivity signal has been found in the case of a partial melting of the thermally grown NiSi2 layers several microseconds after the laser pulse. This decrease has been correlated with the exfoliation of surface materials as found by the scanning electron microscopy of the irradiated samples. Slip planes were also observed after solidification either of a partially melted mixture of A and B type or of a B-type NiSi2 silicide. No exfoliation and a much lower density of slip planes were observed after solidification of a completely melted silicide layer. The dynamics of melting and the damage of the irradiated layers are explained in terms of heat-flow calculation and thermomechanical and mismatch stress.

Materialart: Digitale Medien

URL: http://dx.doi.org/10.1063/1.337927

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10

Digitale Medien

Liquid phase epitaxy of cubic FeSi2 on (111) Si induced by pulsed laser irradiation (1992)

Grimaldi, M. G. ; Baeri, P. ; Spinella, C. ; [weitere]

Woodbury, NY : American Institute of Physics (AIP)

Applied Physics Letters 60 (1992), S. 1132-1134

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ISSN: 1077-3118

Quelle: AIP Digital Archive

Thema: Physik

Notizen: Epitaxial βFeSi2 layers thermally grown on (111) Si substrates have been irradiated by 25 ns ruby laser pulses in the energy density range 0.3–0.7 J/cm2. Rutherford backscattering analyses in combination with the channeling effect have shown that the silicide stoichiometry does not change for irradiations up to an energy density of 0.5 J/cm2, while alignment of the irradiated silicide along the [111] substrate normal direction is observed. Transmission electron diffraction in the plan view configuration showed that this silicide phase has a cubic symmetry with a lattice parameter very similar to that of Si. Diffraction patterns taken along different poles of the substrate indicated that the epitaxial phase is 180° rotated about the [111] normal direction like the B type NiSi2 and CoSi2 silicides.

Materialart: Digitale Medien

URL: http://dx.doi.org/10.1063/1.106430

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