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3. Doppler imaging of the young late-type star LO Pegasi (BD +22 4409) in September 2003

Author

Piluso, N., Lanza, A. F., Pagano, I., Lanzafame, A. C., and Donati, J. -F.

Subjects
Astrophysics
Abstract

A Doppler image of the ZAMS late-type rapidly rotating star LO Pegasi, based on spectra acquired between 12 and 15 September 2003, is presented. The Least Square Deconvolution technique is applied to enhance the signal-to-noise ratio of the mean rotational broadened line profiles extracted from the observed spectra. In the present application, a unbroadened spectrum is used as a reference, instead of a simple line list, to improve the deconvolution technique applied to extract the mean profiles. The reconstructed image is similar to those previously obtained from observations taken in 1993 and 1998, and shows that LO Peg photospheric activity is dominated by high-latitude spots with a non-uniform polar cap. The latter seems to be a persistent feature as it has been observed since 1993 with little modifications. Small spots, observed between ~ 10 and ~ 60 degrees of latitude, appears to be different with respect to those present in the 1993 and 1998 maps., Comment: 21 pages, 10 figures, accepted by Monthly Notices of the Royal Astronomical Society

Published
2008
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11. Sicilia—silicon carbide detectors for intense luminosity investigations and applications

Author

Tudisco, S, La Via, F, Agodi, C, Altana, C, Borghi, G, Boscardin, M, Bussolino, G, Calcagno, L, Camarda, M, Cappuzzello, F, Carbone, D, Cascino, S, Casini, G, Cavallaro, M, Ciampi, C, Cirrone, G, Cuttone, G, Fazzi, A, Giove, D, Gorini, G, Labate, L, Lanzalone, G, Litrico, G, Longo, G, Presti, D, Mauceri, M, Modica, R, Moschetti, M, Muoio, A, Musumeci, F, Pasquali, G, Petringa, G, Piluso, N, Poggi, G, Privitera, S, Puglia, S, Puglisi, V, Rebai, M, Ronchin, S, Santangelo, A, Stefanini, A, Trifiro, A, Zimbone, M, Tudisco S., La Via F., Agodi C., Altana C., Borghi G., Boscardin M., Bussolino G., Calcagno L., Camarda M., Cappuzzello F., Carbone D., Cascino S., Casini G., Cavallaro M., Ciampi C., Cirrone G., Cuttone G., Fazzi A., Giove D., Gorini G., Labate L., Lanzalone G., Litrico G., Longo G., Presti D. L., Mauceri M., Modica R., Moschetti M., Muoio A., Musumeci F., Pasquali G., Petringa G., Piluso N., Poggi G., Privitera S., Puglia S., Puglisi V., Rebai M., Ronchin S., Santangelo A., Stefanini A., Trifiro A., Zimbone M., Tudisco, S, La Via, F, Agodi, C, Altana, C, Borghi, G, Boscardin, M, Bussolino, G, Calcagno, L, Camarda, M, Cappuzzello, F, Carbone, D, Cascino, S, Casini, G, Cavallaro, M, Ciampi, C, Cirrone, G, Cuttone, G, Fazzi, A, Giove, D, Gorini, G, Labate, L, Lanzalone, G, Litrico, G, Longo, G, Presti, D, Mauceri, M, Modica, R, Moschetti, M, Muoio, A, Musumeci, F, Pasquali, G, Petringa, G, Piluso, N, Poggi, G, Privitera, S, Puglia, S, Puglisi, V, Rebai, M, Ronchin, S, Santangelo, A, Stefanini, A, Trifiro, A, Zimbone, M, Tudisco S., La Via F., Agodi C., Altana C., Borghi G., Boscardin M., Bussolino G., Calcagno L., Camarda M., Cappuzzello F., Carbone D., Cascino S., Casini G., Cavallaro M., Ciampi C., Cirrone G., Cuttone G., Fazzi A., Giove D., Gorini G., Labate L., Lanzalone G., Litrico G., Longo G., Presti D. L., Mauceri M., Modica R., Moschetti M., Muoio A., Musumeci F., Pasquali G., Petringa G., Piluso N., Poggi G., Privitera S., Puglia S., Puglisi V., Rebai M., Ronchin S., Santangelo A., Stefanini A., Trifiro A., and Zimbone M.

Abstract

Silicon carbide (SiC) is a compound semiconductor, which is considered as a possible alternative to silicon for particles and photons detection. Its characteristics make it very promising for the next generation of nuclear and particle physics experiments at high beam luminosity. Silicon Carbide detectors for Intense Luminosity Investigations and Applications (SiCILIA) is a project starting as a collaboration between the Italian National Institute of Nuclear Physics (INFN) and IMM-CNR, aiming at the realization of innovative detection systems based on SiC. In this paper, we discuss the main features of silicon carbide as a material and its potential application in the field of particles and photons detectors, the project structure and the strategies used for the prototype realization, and the first results concerning prototype production and their performance.

Published
2018

13. A novel micro-Raman technique to detect and characterize 4H-SiC stacking faults.

Author

Piluso, N., Camarda, M., and La Via, F.

Subjects
*RAMAN scattering, *STACKING machines, *MORPHOLOGY, *HOMOEPITAXY, *PHOTOLUMINESCENCE
Abstract

A novel Micro-Raman technique was designed and used to detect extended defects in 4H-SiC homoepitaxy. The technique uses above band-gap high-power laser densities to induce a local increase of free carriers in undoped epitaxies (n<1016 at/cm-3), creating an electronic plasma that couples with the longitudinal optical (LO) Raman mode. The Raman shift of the LO phononplasmon- coupled mode (LOPC) increases as the free carrier density increases. Crystallographic defects lead to scattering or recombination of the free carriers which results in a loss of coupling with the LOPC, and in a reduction of the Raman shift. Given that the LO phonon-plasmon coupling is obtained thanks to the free carriers generated by the high injection level induced by the laser, we named this technique induced-LOPC (i-LOPC). This technique allows the simultaneous determination of both the carrier lifetime and carrier mobility. Taking advantage of the modifications on the carrier lifetime induced by extended defects, we were able to determine the spatial morphology of stacking faults; the obtained morphologies were found to be in excellent agreement with those provided by standard photoluminescence techniques. The results show that the detection of defects via i-LOPC spectroscopy is totally independent from the stacking fault photoluminescence signals that cover a large energy range up to 0.7 eV, thus allowing for a single-scan simultaneous determination of any kind of stacking fault. Combining the i-LOPC method with the analysis of the transverse optical mode, the micro-Raman characterization can determine the most important properties of unintentionally doped film, including the stress status of the wafer, lattice impurities (point defects, polytype inclusions) and a detailed analysis of crystallographic defects, with a high spectral and spatial resolution. [ABSTRACT FROM AUTHOR]

Published
2014
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14. Defect reduction in epitaxial 3C-SiC on Si(001) and Si(111) by deep substrate patterning

Author

von Känel, H, MIGLIO, LEONIDA, Crippa, D, Kreiliger, T, Mauceri, M, Puglisi, M, Mancarella, F, Anzalone, R, Piluso, N, La Via, F., Chaussende, D, Ferro, G, von Känel, H, Miglio, L, Crippa, D, Kreiliger, T, Mauceri, M, Puglisi, M, Mancarella, F, Anzalone, R, Piluso, N, and La Via, F

Subjects
Wafer bowing, Mechanics of Materials, Mechanical Engineering, Patterned substrate, Materials Science (all), Condensed Matter Physic, Stacking fault reduction, 3C-SiC, Low-pressure chemical vapor deposition, FIS/03 - FISICA DELLA MATERIA, Heteroepitaxy
Abstract

The heteroepitaxial growth of 3C-SiC on Si(001) and Si(111) substrates deeply patterned at a micrometer scale by low-pressure chemical vapor deposition is shown to lead to space-filling isolated structures resulting from a mechanism of self-limitation of lateral expansion. Stacking fault densities and wafer bowing may be drastically reduced for optimized pattern geometries.

Published
2015

18. Defect reduction in epitaxial 3C-SiC on Si(001) and Si(111) by deep substrate patterning

Author

Chaussende, D, Ferro, G, von Känel, H, Miglio, L, Crippa, D, Kreiliger, T, Mauceri, M, Puglisi, M, Mancarella, F, Anzalone, R, Piluso, N, La Via, F, MIGLIO, LEONIDA, La Via, F., Chaussende, D, Ferro, G, von Känel, H, Miglio, L, Crippa, D, Kreiliger, T, Mauceri, M, Puglisi, M, Mancarella, F, Anzalone, R, Piluso, N, La Via, F, MIGLIO, LEONIDA, and La Via, F.

Abstract

The heteroepitaxial growth of 3C-SiC on Si(001) and Si(111) substrates deeply patterned at a micrometer scale by low-pressure chemical vapor deposition is shown to lead to space-filling isolated structures resulting from a mechanism of self-limitation of lateral expansion. Stacking fault densities and wafer bowing may be drastically reduced for optimized pattern geometries.

Published
2015

19. Micro-Raman analysis and finite-element modeling of 3 C-SiC microstructures

Author

Piluso N, Anzalone R, Camarda M, Severino A, La Magna A, D'Arrigo G, and La Via F

Abstract

Micro- and nano-electromechanical systems (MEMS and NEMS) fabricated in 3?C-SiC are receiving particular attention thanks to the material physical properties: its wide band gap (2.3?eV), its ability to operate at high temperatures, its mechanical strength and its inertness to the exposure in corrosive environments. However, high residual stress (which is normally generated during the hetero-epitaxial growth process) makes the use of 3?C-SiC in Si-based MEMS fabrication techniques very limited leading to a failure of micro-machined/sensor structures. In this paper, micro-Raman characterizations and finite-element modeling (FEM) of microstructures realized on poly and single-crystal (100) 3?C-SiC/Si films are performed. Transverse optical (TO) Raman mode analysis reveals the stress relaxation on the free standing structure (796.5?cm-1) respect to the stressed unreleased region (795.7?cm-1). Also, microstructures as cantilever, bridge and planar rotating probe show an intense stress field located around the undercut region. Here, the TO Raman mode undergoes an intense shift, up to 2?cm-1, ascribed to the modification of the Raman stress tensor. Indeed, the generalized axial regime, described by diagonal components of the Raman stress tensor, cannot be applied in this region. Raman maps analysis and FEM simulations show the activation of the shear stress, i.e. non-diagonal components of the stress tensor. The stress-Raman modes shift correlation, in the case of fully non-diagonal stress tensors, has been investigated. The aim of future works will be to minimize the stress field generation and the defects density within the epitaxial layer.

Published
2013
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20. Crystal recovery from Al-implantation induced damaging in 3C-SiC films

Author

Severino A, Piluso N, Marino A, and La Via F

Subjects
NITROGEN, THIN-FILMS, stomatognathic system, DEFECTS
Abstract

Damaging in Al-implanted 3C-SiC and subsequent crystal recovery due to thermal treatments up to 1350 degrees C are evaluated by X-ray diffraction and micro-Raman spectroscopy. Reciprocal space mapping of (004) 3C-SiC planes shows a low-intensity implantation-induced secondary peak at higher interplanar spacing in the as-implanted 3C-SiC sample, with a generated misfit between the implanted and the epitaxial region of about 0.6%. Increasing the annealing temperature from 950 degrees C to 1350 angstrom C, the secondary peak is gradually re-absorbed within the epitaxial 3C-SiC reciprocal lattice point. Finally, the disappearance of the secondary peak after a 1350 degrees C thermal treatment is observed. Thus, implantation-induced average strain, resulting in a severe 3C-SiC deforma- tion, has been totally relieved at the highest annealing temperature.

Published
2012

21. Defect Influence on Heteroepitaxial 3C-SiC Young's Modulus

Author

Anzalone R, Camarda M, Canino A, Piluso N, La Via F, and D'Arrigo G

Abstract

Heteroepitaxial cubic silicon carbide (3C-SiC) is an extremely promising material for micro-and nano-electromechanical systems due to its large Young's modulus. Unfortunately, the heteroepitaxy of 3C-SiC on Si substrate is affected by the high mismatch in the lattice parameters and the thermal expansion coefficients between the two dissimilar materials that generate a high number of defects in the material. In this work, through the measurement of natural resonant frequencies and Raman shift analysis, a strong relationship between the mechanical proprieties of the material (Young's modulus) and the film crystal quality (defect density) was observed.

Published
2011

23. Optical investigation of bulk electron mobility in 3C-SiC films on Si substrates

Author

Piluso N, Severino A, Camarda M, Canino A, La Magna A, and La Via F

Abstract

The dependence between the carrier concentration and electrical mobility has been studied by micro-Raman spectroscopy in n-doped 3C-SiC films grown on (111) and (100) Silicon oriented substrates. Bulk mobility varies between 10 and 510 cm(2) V-1 s(-1) for a carrier concentration ranging between 1.6 X 10(16) and 5.4 X 10(18) cm(-3). Local stacking variations observed on the (111) 3C-SiC surface lead to a worse crystal morphology compared to (100) 3C-SiC films resulting in a decrease in the average bulk mobility. Defects are thus accountable for the dependence between mobility and carrier concentration for different 3C-SiC orientations.

Published
2010

27. Three-dimensional EpitaxialSi1-xGex, Ge and SiC Crystals onDeeply Patterned Si substrates

Author

von Känel, H, Isa, F, Falub, C, Barthazy, E, Müller, E, Chrastina, D, Isella, G, Kreiliger, T, Taboada, A, Meduňa, M, Kaufmann, R, Neels, A, Dommann, A, Niedermann, P, Mancarella, F, Mauceri, M, Puglisi, M, Crippa, D, La Via, F, Anzalone, R, Piluso, N, Bergamaschini, R, Marzegalli, A, Miglio, L, Falub, CV, Barthazy, EJ, Taboada, AG, BERGAMASCHINI, ROBERTO, MARZEGALLI, ANNA, MIGLIO, LEONIDA, von Känel, H, Isa, F, Falub, C, Barthazy, E, Müller, E, Chrastina, D, Isella, G, Kreiliger, T, Taboada, A, Meduňa, M, Kaufmann, R, Neels, A, Dommann, A, Niedermann, P, Mancarella, F, Mauceri, M, Puglisi, M, Crippa, D, La Via, F, Anzalone, R, Piluso, N, Bergamaschini, R, Marzegalli, A, Miglio, L, Falub, CV, Barthazy, EJ, Taboada, AG, BERGAMASCHINI, ROBERTO, MARZEGALLI, ANNA, and MIGLIO, LEONIDA

Abstract

We show that geometric shielding of the reactive flux in chemical vapor deposition by tall neighboring structures obtained by deep substrate patterning, along with short surface diffusion lengths, can provide nearly space filling arrays of high-quality epitaxial crystals despite large mismatches of lattice parameters and thermal expansion coefficients. The density of extended defects is strongly reduced by the method, and wafer bowing and crack formation largely inhibited. The concept is shown to be valid for SiGe/Si heterostructures ranging from pure Si to pure Ge both on Si(001) and Si(111) substrates. Here, dislocations are efficiently eliminated from three-dimensional faceted crystals with high-aspect ratios on top of micron-sized Si pillars. The application to 3C-SiC/Si(001) ridges, characterized by a lattice mismatch of nearly 20%, provides significantly lower stacking fault densities compared with layers grown on planar substrates

Published
2014

29. Impact of substrate steps and of monolayer-bilayer junctions on the electronic transport in epitaxial graphene on 4H-SiC (0001)

Author

Giannazzo, F., Deretzis, I., La Magna, A., Di Franco, S., Piluso, N., Fiorenza, P., Roccaforte, F., Schmid, P., Lerch, W., Yakimova, Rositsa, Giannazzo, F., Deretzis, I., La Magna, A., Di Franco, S., Piluso, N., Fiorenza, P., Roccaforte, F., Schmid, P., Lerch, W., and Yakimova, Rositsa

Abstract

Two dimensional maps of the electronic conductance in epitaxial graphene (EG) grown on SiC were obtained by conductive atomic force microscopy (CAFM). The correlation between morphological and electrical maps revealed the local conductance degradation in EG over the SiC substrate steps or at the junction between monolayer (1L) and bilayer (2L) graphene regions. The effect of steps strongly depends on the charge transfer phenomena between the step sidewall and graphene, whereas the resistance increase at 1L/2L junction is a purely quantum mechanical effect, due to the weak coupling between 1L and 2L electron wavefunctions.

Published
2013
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48. Micro-Raman analysis and finite-element modeling of 3 C-SiC microstructures.

Author

Piluso, N., Anzalone, R., Camarda, M., Severino, A., La Magna, A., D'Arrigo, G., and La Via, F.

Abstract

Micro- and nano-electromechanical systems (MEMS and NEMS) fabricated in 3 C-SiC are receiving particular attention thanks to the material physical properties: its wide band gap (2.3 eV), its ability to operate at high temperatures, its mechanical strength and its inertness to the exposure in corrosive environments. However, high residual stress (which is normally generated during the hetero-epitaxial growth process) makes the use of 3 C-SiC in Si-based MEMS fabrication techniques very limited leading to a failure of micro-machined/sensor structures. In this paper, micro-Raman characterizations and finite-element modeling (FEM) of microstructures realized on poly and single-crystal (100) 3 C-SiC/Si films are performed. Transverse optical (TO) Raman mode analysis reveals the stress relaxation on the free standing structure (796.5 cm−1) respect to the stressed unreleased region (795.7 cm−1). Also, microstructures as cantilever, bridge and planar rotating probe show an intense stress field located around the undercut region. Here, the TO Raman mode undergoes an intense shift, up to 2 cm−1, ascribed to the modification of the Raman stress tensor. Indeed, the generalized axial regime, described by diagonal components of the Raman stress tensor, cannot be applied in this region. Raman maps analysis and FEM simulations show the 'activation' of the shear stress, i.e. non-diagonal components of the stress tensor. The stress-Raman modes shift correlation, in the case of fully non-diagonal stress tensors, has been investigated. The aim of future works will be to minimize the stress field generation and the defects density within the epitaxial layer. Copyright © 2012 John Wiley & Sons, Ltd. [ABSTRACT FROM AUTHOR]

Published
2013
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49. On the determination of diameter distribution in multi-wall carbon nanotubes by Raman spectroscopy: issues related to excitation laser energy.

Author

Scalese, S., Scuderi, V., Bagiante, S., Deretzis, I., La Magna, A., Bongiorno, C., Compagnini, G., Gibilisco, S., Piluso, N., and Privitera, V.

Abstract

Multi-wall carbon nanotubes (MWCNTs) produced by the arc discharge between two graphite rods in liquid nitrogen have been investigated with the use of Raman spectroscopy and transmission electron microscopy (TEM). The effects of the applied voltage on the structural properties of the produced MWCNTs have been observed, in particular, as it concerns the size of the innermost and outermost diameters. The apparent discrepancies observed between the Raman and TEM results are explained through the observation of a selective response of the MWCNTs to the excitation laser energy in Raman spectroscopy, similar to the case of single-wall CNTs. Electronic structure calculations correlate such behavior with optical transitions, in the presence of strong electronic localizations, spatially confined in a few neighboring walls. Copyright © 2011 John Wiley & Sons, Ltd. [ABSTRACT FROM AUTHOR]

Published
2012
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