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413 results on '"Veje E"'

1. Thermal and optical properties of porous silicon

Author

Silva A. Ferreira da, Silva T. Souza da, Nakamura O., d?Aguiar Neto M.M.F., Pepe I., Roman L. S., and Veje E.

Subjects
thermal properties, optical properties, photoacoustic spectroscopy, porous silicon, Materials of engineering and construction. Mechanics of materials, TA401-492
Abstract

Thermal diffusivity and optical absorption have been investigated for porous silicon, at room temperature, using photoacoustic spectroscopy. The experimental results obtained conform well with the existing studies recently published. The value obtained for thermal diffusivity is 0.045 ± 0.002 cm²/s.The absorption onsets show energy structures, differing from the ordinary semiconductor of bulk type.

Published
2001

6. Test results of full-scale HTS cable models and plans for a 36 kV, 2kArms utility demonstration

Author

Willen, D.W.A., Hansen, F., Rasmussen, C.N., Daumling, M., Schuppach, O.E., Hansen, E., Baerentzen, J., Svarrer-Hansen, B., Traeholt, Chresten, Olsen, S.K., Rasmussen, C., Veje, E., Jensen, K.H., Tonnesen, O., Ostergaard, J., Mikkelsen, S.D., Mortensen, J., and Dam-Andersen, M.

Subjects
High temperature superconductors -- Research, Business, Electronics, Electronics and electrical industries
Abstract

The construction, installation and operation of an entire hight temperature superconducting cable system in a power utility is examined.

Published
2001

14. Electronic and optical properties of lead iodide.

Author

Ahuja, R., Arwin, H., Ferreira da Silva, A., Persson, C., Osorio-Guillén, J. M., Souza de Almeida, J., Moyses Araujo, C., Veje, E., Veissid, N., An, C. Y., Pepe, I., and Johansson, B.

Subjects
IODIDES, LEAD
Abstract

The electronic properties and the optical absorption of lead iodide (PbI[sub 2]) have been investigated experimentally by means of optical absorption and spectroscopic ellipsometry, and theoretically by a full-potential linear muffin-tin-orbital method. PbI[sub 2] has been recognized as a very promising detector material with a large technological applicability. Its band-gap energy as a function of temperature has also been measured by optical absorption. The temperature dependence has been fitted by two different relations, and a discussion of these fittings is given. [ABSTRACT FROM AUTHOR]

Published
2002
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27. Journal of Applied Physics

Author

Ahuja, Rajeev, Arwin, Hans, Silva, A. Ferreira da, Araújo, Carlos Moysés, Veje, E., Pepe, Iuri Muniz, and Johansson, B.

Abstract

p. 7219-7224 Submitted by Suelen Reis (suelen_suzane@hotmail.com) on 2012-12-10T19:58:42Z No. of bitstreams: 1 http___scitation.aip.org_getpdf_servlet_GetPDFServlet_filetype=pdf&id=JAPIAU000092000012007219000001&idtype=cvips&doi=10.1063_1.pdf: 348413 bytes, checksum: e1d79cb78a198daba8be3bab49a59215 (MD5) Made available in DSpace on 2012-12-10T19:58:42Z (GMT). No. of bitstreams: 1 http___scitation.aip.org_getpdf_servlet_GetPDFServlet_filetype=pdf&id=JAPIAU000092000012007219000001&idtype=cvips&doi=10.1063_1.pdf: 348413 bytes, checksum: e1d79cb78a198daba8be3bab49a59215 (MD5) Previous issue date: 2002-12 The electronic properties and the optical absorption of lead iodide (PbI2) have been investigated experimentally by means of optical absorption and spectroscopic ellipsometry, and theoretically by a full-potential linear muffin-tin-orbital method. PbI2 has been recognized as a very promising detector material with a large technological applicability. Its band-gap energy as a function of temperature has also been measured by optical absorption. The temperature dependence has been fitted by two different relations, and a discussion of these fittings is given.

Published
2002
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28. Thermal and optical properties of porous silicon

Author

Silva, A. Ferreira da, Silva, T. Souza da, Nakamura, O., d’Aguiar Neto, M.M.F., Pepe, I., Roman, L. S., and Veje, E.

Subjects
optical properties, photoacoustic spectroscopy, porous silicon, thermal properties
Abstract

Thermal diffusivity and optical absorption have been investigated for porous silicon, at room temperature, using photoacoustic spectroscopy. The experimental results obtained conform well with the existing studies recently published. The value obtained for thermal diffusivity is 0.045 ± 0.002 cm²/s.The absorption onsets show energy structures, differing from the ordinary semiconductor of bulk type.

Published
2001

29. Materials Research

Author

Silva, A. Ferreira da, Silva, T. Souza da, Nakamura, Ossamu, D'Aguiar Neto, Manoel Marcos Freire, Pepe, Iuri Muniz, Roman, L. S., and Veje, E.

Subjects
Thermal properties, Optical properties, Porous silicon, Photoacoustic spectroscopy
Abstract

p. 23-26. Submitted by JURANDI DE SOUZA SILVA (jssufba@hotmail.com) on 2011-12-20T10:58:58Z No. of bitstreams: 1 a06v04n1.pdf: 60800 bytes, checksum: b13568c59842ab72b190afaf6640031d (MD5) Made available in DSpace on 2011-12-20T10:58:58Z (GMT). No. of bitstreams: 1 a06v04n1.pdf: 60800 bytes, checksum: b13568c59842ab72b190afaf6640031d (MD5) Previous issue date: 2001-01 Thermal diffusivity and optical absorption have been investigated for porous silicon, at room temperature, using photoacoustic spectroscopy. The experimental results obtained conform well with the existing studies recently published. The value obtained for thermal diffusivity is 0.045 ± 0.002 cm2/s.The absorption onsets show energy structures, differing from the ordinary semiconductor of bulk type. PACS 51.20.Td; 74.25.Fy; 73.20.Dy; 78.20.Wc; 81.40.Tv São Carlos

Published
2001

30. Solid State Communications

Author

Silva, A. Ferreira da, Rosa, R.R., Roman, L.S., Veje, E., and Pepe, Iuri Muniz

Subjects
A. Semiconductors, B. Nanofabrications, D. Optical properties, C. Crystal structure and symmetry
Abstract

Texto completo: acesso restrito. p.703-708 Submitted by Suelen Reis (suelen_suzane@hotmail.com) on 2013-01-17T10:47:15Z No. of bitstreams: 1 silva.pdf: 307236 bytes, checksum: 74ea16a56cbffa0377ac24464497b55e (MD5) Made available in DSpace on 2013-01-17T10:47:15Z (GMT). No. of bitstreams: 1 silva.pdf: 307236 bytes, checksum: 74ea16a56cbffa0377ac24464497b55e (MD5) Previous issue date: 2000 Due to possible technological applications in opto-electronic devices, the interest in characterizing porous silicon structure patterns has recently increased. From scanning force microscopy (SFM) we have obtained images of different samples of porous silicon and applied pattern characterization operators on these matrices. In this paper, asymmetric spatial fragmentation in amplitude envelopes of porous silicon samples are characterized by means of a parameter that quantifies the amount of spatial asymmetry in the gradient field. The results show that this method is well suited to characterize silicon porosity quantitatively.

Published
2000
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31. Journal of Porous Materials

Author

Egeberg, R. C., Veje, E., Silva, A. Ferreira da, Pepe, Iuri Muniz, and Alves, A. Santos

Subjects
porous silicon, photoacoustic spectroscopy, energy band
Abstract

Texto completo: acesso restrito. p.173-176 Submitted by Suelen Reis (suelen_suzane@hotmail.com) on 2013-01-17T10:41:00Z No. of bitstreams: 1 Veje.pdf: 36072 bytes, checksum: fc6b0bd61589b0e9f2b55647c613efad (MD5) Made available in DSpace on 2013-01-17T10:41:00Z (GMT). No. of bitstreams: 1 Veje.pdf: 36072 bytes, checksum: fc6b0bd61589b0e9f2b55647c613efad (MD5) Previous issue date: 2000 Porous silicon has been studied with photoluminescence, photoluminescence excitation, and photoacoustic spectroscopy. From the luminescence data, an energy-level diagram related to the luminescence is constructed. The diagram is confirmed in detail by the photoacoustic spectra. The results are discussed with the conclusion that they are in good agreement with the surface-band oxyhydride-like emitter, which recently has been established as the source for the photoluminescence from porous silicon.

Published
2000
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32. Modeling and gradient pattern analysis of irregular SFM structures of porous silicon

Author

Baroni, Mpma, Rosa, R. R., da Silva, A. F., Pepe, I., Roman, L. S., Ramos, F. M., Ahuja, Rajeev, Persson, Clas, Veje, E., Baroni, Mpma, Rosa, R. R., da Silva, A. F., Pepe, I., Roman, L. S., Ramos, F. M., Ahuja, Rajeev, Persson, Clas, and Veje, E.

Abstract

Technological applications in opto-electronic devices have increased the interest in characterizing porous silicon structure patterns. Due to its physical properties, solutions from KPZ 2D are adopted to simulate the structure of porous material interface whose spatial characteristics are equivalent to those found in porous silicon samples. The analysis of the simulated and real scanning Force Microscopy (SFM) surfaces was done using the Gradient Pattern Analysis (GPA). We found that the KPZ 2D model presented asymmetry levels compatible with the irregular surfaces observed by means of SFM images of pi-Si., QC 20100525

Published
2006
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33. Electronic and optical properties of lead iodide

Author

Ahuja, Rajeev, Arwin, H., Ferreira da Silva, A., Persson, C., Osorio-Guillén, J. M., Souza de Almeida, J., Araujo, C. Moyses, Veje, E., Veissid, N., An, C. Y., Ahuja, Rajeev, Arwin, H., Ferreira da Silva, A., Persson, C., Osorio-Guillén, J. M., Souza de Almeida, J., Araujo, C. Moyses, Veje, E., Veissid, N., and An, C. Y.

Abstract

The electronic properties and the optical absorption of lead iodide (PbI2) have been investigated experimentally by means of optical absorption and spectroscopic ellipsometry, and theoretically by a full-potential linear muffin-tin-orbital method. PbI2 has been recognized as a very promising detector material with a large technological applicability. Its band-gap energy as a function of temperature has also been measured by optical absorption. The temperature dependence has been fitted by two different relations, and a discussion of these fittings is given.

Published
2002
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34. The electrical band-gap energy of porous silicon measured versus sample temperature

Author

Frederiksen, Jacob Trier, Melcher, Pia Grethe, Veje, E, Frederiksen, Jacob Trier, Melcher, Pia Grethe, and Veje, E

Abstract

Photocurrent measurements have been carried out on a series of samples consisting of porous silicon on top of crystalline silicon, in the temperature range 10-300 K. From the experimental data set, the electrical band-gap energy of porous silicon is deduced to be (1.80 ±0.01) eV, independent of sample temperature. The results are discussed with the conclusion that for the samples studied here, the electrical bandgap in porous silicon is of molecular nature and cannot be related to quantum-confinement properties of nanocrystals of elemental silicon.

Published
2000

35. Characterization of asymmetric fragmentation patterns in SFM images of porous silicon

Author

Ferreira, Da Silva A., Rosa, R.R., Roman, L.S., Veje, E., Pepe, I., Ferreira, Da Silva A., Rosa, R.R., Roman, L.S., Veje, E., and Pepe, I.

Abstract

Due to possible technological applications in opto-electronic devices, the interest in characterizing porous silicon structure patterns has recently increased. From scanning force microscopy (SFM) we have obtained images of different samples of porous silicon and applied pattern characterization operators on these matrices. In this paper, asymmetric spatial fragmentation in amplitude envelopes of porous silicon samples are characterized by means of a parameter that quantifies the amount of spatial asymmetry in the gradient field. The results show that this method is well suited to characterize silicon porosity quantitatively.

Published
2000
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36. Asymmetric nonlinear amplitude in patterns of porous silicon

Author

Da, Silva A.F., Rosa, R.R., MacHado, P.W.A., Ramos, F.M., Neto, C.R., Roman, E.L.S., Veje, E., Da, Silva A.F., Rosa, R.R., MacHado, P.W.A., Ramos, F.M., Neto, C.R., Roman, E.L.S., and Veje, E.

Abstract

A gradient pattern analysis is used to report a phenomenogical evidence of asymmetric nonlinear spatial distribution of porous silicon structures. We used a canonical sample set obtained from scanning force microscopy. Due to the high sensitivity of the gradient field operator, it is possible to correlate the photoluminescence performance of porous silicon with different degree of asymmetries and spatial nonlinearity. A generalization of this new approach to quantify nonlinear amplitude fragmentation in complex lattices is proposed.

Published
2000
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37. Beam-foil-gas spectroscopy - A technique for studying steady-state non-equilibrium processes.

Author

Bickel, W. S, Veje, E, Carriveau, G, and Anderson, N

Subjects
Chemistry
Abstract

When a thin foil is inserted in the beam of a beam-gas experiment, the beam particle state populations are driven far from their beam-gas equilibrium values. Downstream from the foil, the 'new beam' and gas species interact to produce a new equilibrium, usually different from the beam-gas equilibrium. Experimental results are presented to demonstrate this effect and to show how relative cross-section measurements can be used to study the beam-foil interaction.

Published
1971

38. Electrical band-gap energy of porous silicon and the band offsets at the porous-silicon/crystalline-silicon heterojunction measured versus sample temperature

Author

Frederiksen, Jacob Trier, Melcher, Pia Grethe, Veje, E., Frederiksen, Jacob Trier, Melcher, Pia Grethe, and Veje, E.

Abstract

Photocurrent measurements have been carried out on a series of samples consisting of porous silicon on top of crystalline silicon, in the temperature range 10–300 K. From the experimental data set, the electrical band-gap energy of porous silicon is deduced to be (1.8060.01) eV, independent of sample temperature. In contrast to this, some temperature variations are observed for the band offsets, reflecting qualitatively the temperature dependence of the fundamental band-gap energy of crystalline silicon. However, whereas the latter decreases monotonically for increasing temperature, a maximum is observed at around 125 K for the conduction-band offset together with a corresponding minimum for the valence-band offset. The results are discussed with the conclusion that for the samples studied here, the electrical band gap in porous silicon is of a molecular nature and cannot be related to quantum-confinement properties of nanocrystals of elemental silicon.

Published
1998

46. Test results of full-scale high temperature superconductors cable models destined for a 36 kV, 2 kArms utility demonstration

Author

Däumling, M., primary, Rasmussen, C.N., additional, Hansen, F., additional, Willén, D.W.A., additional, Schuppach, O.E., additional, Hansen, B.S., additional, Træholt, C., additional, Jensen, K.H., additional, Olsen, S.K., additional, Rasmussen, C., additional, Veje, E., additional, Tønnesen, O., additional, and Østergaard, J., additional

Published
2001
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47. Test results of full-scale HTS cable models and plans for a 36 kV, 2 kA/sub rms/ utility demonstration

Author

Willen, D.W.A., primary, Hansen, F., additional, Rasmussen, C.N., additional, Daumling, M., additional, Schuppach, O.E., additional, Hansen, E., additional, Baerentzen, J., additional, Svarrer-Hansen, B., additional, Traeholt, C., additional, Olsen, S.K., additional, Ramussen, C., additional, Veje, E., additional, Jensen, K.H., additional, Tonnesen, O., additional, Ostergaard, J., additional, Mikkelsen, S.D., additional, Mortensen, J., additional, and Dam-Andersen, M., additional

Published
2001
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