Documents disponibles écrits par cet auteur

Criteria for cross-plane dominated thermal transport in multilayer thin film systems during modulated laser heating / Patrick E. Hopkins in Journal of heat transfer, Vol. 132 N° 8 (Août 2010) 

Public ISBD [article]  in Journal of heat transfer > Vol. 132 N° 8 (Août 2010) . - pp. [081302-1/10] Titre : Criteria for cross-plane dominated thermal transport in multilayer thin film systems during modulated laser heating Type de document : texte imprimé Auteurs : Patrick E. Hopkins, Auteur ; Justin R. Serrano, Auteur ; Leslie M. Phinney, Auteur Article en page(s) : pp. [081302-1/10] Note générale : Physique Langues : Anglais (eng) Mots-clés : Pump-probe  thermoreflectance  Thin  film  thermal  conductivity  Thermal  boundary  conductance  Radial  heating  Cross-plane  transport Index. décimale : 536 Chaleur. Thermodynamique Résumé : Pump-probe transient thermoreflectance (TTR) techniques are powerful tools for measuring the thermophysical properties of thin films, such as thermal conductivity, Lambda, or thermal boundary conductance, G. This paper examines the assumption of one-dimensional heating on, Lambda and G, determination in nanostructures using a pump-probe transient thermoreflectance technique. The traditionally used one-dimensional and axially symmetric cylindrical conduction models for thermal transport are reviewed. To test the assumptions of the thermal models, experimental data from Al films on bulk substrates (Si and glass) are taken with the TTR technique. This analysis is extended to thin film multilayer structures. The results show that at 11 MHz modulation frequency, thermal transport is indeed one dimensional. Error among the various models arises due to pulse accumulation and not accounting for residual heating. DEWEY : 536 ISSN : 0022-1481 En ligne : http://asmedl.aip.org/vsearch/servlet/VerityServlet?KEY=JHTRAO&ONLINE=YES&smode= [...] [article] Criteria for cross-plane dominated thermal transport in multilayer thin film systems during modulated laser heating [texte imprimé] / Patrick E. Hopkins, Auteur ; Justin R. Serrano, Auteur ; Leslie M. Phinney, Auteur . - pp. [081302-1/10]. Physique Langues : Anglais (eng) in Journal of heat transfer > Vol. 132 N° 8 (Août 2010) . - pp. [081302-1/10] Mots-clés : Pump-probe  thermoreflectance  Thin  film  thermal  conductivity  Thermal  boundary  conductance  Radial  heating  Cross-plane  transport Index. décimale : 536 Chaleur. Thermodynamique Résumé : Pump-probe transient thermoreflectance (TTR) techniques are powerful tools for measuring the thermophysical properties of thin films, such as thermal conductivity, Lambda, or thermal boundary conductance, G. This paper examines the assumption of one-dimensional heating on, Lambda and G, determination in nanostructures using a pump-probe transient thermoreflectance technique. The traditionally used one-dimensional and axially symmetric cylindrical conduction models for thermal transport are reviewed. To test the assumptions of the thermal models, experimental data from Al films on bulk substrates (Si and glass) are taken with the TTR technique. This analysis is extended to thin film multilayer structures. The results show that at 11 MHz modulation frequency, thermal transport is indeed one dimensional. Error among the various models arises due to pulse accumulation and not accounting for residual heating. DEWEY : 536 ISSN : 0022-1481 En ligne : http://asmedl.aip.org/vsearch/servlet/VerityServlet?KEY=JHTRAO&ONLINE=YES&smode= [...]

Raman thermometry measurements and thermal simulations for MEMS bridges at pressures from 0.05 torr to 625 torr / Leslie M. Phinney in Journal of heat transfer, Vol. 132 N° 7 (Juillet 2010)

Public ISBD [article]  in Journal of heat transfer > Vol. 132 N° 7 (Juillet 2010) . - pp. [072402-1/9] Titre : Raman thermometry measurements and thermal simulations for MEMS bridges at pressures from 0.05 torr to 625 torr Type de document : texte imprimé Auteurs : Leslie M. Phinney, Auteur ; Justin R. Serrano, Auteur ; Edward S. Piekos, Auteur Article en page(s) : pp. [072402-1/9] Note générale : Physique Langues : Anglais (eng) Mots-clés : Raman  thermometry  MEMS  Finite  element  heat  conduction  simulations  Non-continuum  gas-phase  heat-transfer  model  Low-pressure  effects  Suspended  microbridge Index. décimale : 536 Chaleur. Thermodynamique Résumé : This paper reports on experimental and computational investigations into the thermal performance of microelectromechanical systems (MEMS) as a function of the pressure of the surrounding gas. High spatial resolution Raman thermometry was used to measure the temperature profiles on electrically heated, polycrystalline silicon bridges that are nominally 10 µm wide, 2.25 µm thick, and either 200 µm or 400 µm long in nitrogen atmospheres with pressures ranging from 0.05 Torr to 625 Torr (6.67 Pa–83.3 kPa). Finite element modeling of the thermal behavior of the MEMS bridges is performed and compared with the experimental results. Noncontinuum gas effects are incorporated into the continuum finite element model by imposing temperature discontinuities at gas-solid interfaces that are determined from noncontinuum simulations. The results indicate that gas-phase heat transfer is significant for devices of this size at ambient pressures but becomes minimal as the pressure is reduced below 5 Torr. The model and experimental results are in qualitative agreement, and better quantitative agreement requires increased accuracy in the geometrical and material property values. DEWEY : 536 ISSN : 0022-1481 [article] Raman thermometry measurements and thermal simulations for MEMS bridges at pressures from 0.05 torr to 625 torr [texte imprimé] / Leslie M. Phinney, Auteur ; Justin R. Serrano, Auteur ; Edward S. Piekos, Auteur . - pp. [072402-1/9]. Physique Langues : Anglais (eng) in Journal of heat transfer > Vol. 132 N° 7 (Juillet 2010) . - pp. [072402-1/9] Mots-clés : Raman  thermometry  MEMS  Finite  element  heat  conduction  simulations  Non-continuum  gas-phase  heat-transfer  model  Low-pressure  effects  Suspended  microbridge Index. décimale : 536 Chaleur. Thermodynamique Résumé : This paper reports on experimental and computational investigations into the thermal performance of microelectromechanical systems (MEMS) as a function of the pressure of the surrounding gas. High spatial resolution Raman thermometry was used to measure the temperature profiles on electrically heated, polycrystalline silicon bridges that are nominally 10 µm wide, 2.25 µm thick, and either 200 µm or 400 µm long in nitrogen atmospheres with pressures ranging from 0.05 Torr to 625 Torr (6.67 Pa–83.3 kPa). Finite element modeling of the thermal behavior of the MEMS bridges is performed and compared with the experimental results. Noncontinuum gas effects are incorporated into the continuum finite element model by imposing temperature discontinuities at gas-solid interfaces that are determined from noncontinuum simulations. The results indicate that gas-phase heat transfer is significant for devices of this size at ambient pressures but becomes minimal as the pressure is reduced below 5 Torr. The model and experimental results are in qualitative agreement, and better quantitative agreement requires increased accuracy in the geometrical and material property values. DEWEY : 536 ISSN : 0022-1481

Re-examining electron-fermi relaxation in gold films with a nonlinear thermoreflectance model / Patrick E. Hopkins in Journal of heat transfer, Vol. 133 N° 4 (Avril 2011) 

Public ISBD [article]  in Journal of heat transfer > Vol. 133 N° 4 (Avril 2011) . - pp. [044505/1-4] Titre : Re-examining electron-fermi relaxation in gold films with a nonlinear thermoreflectance model Type de document : texte imprimé Auteurs : Patrick E. Hopkins, Auteur ; Leslie M. Phinney, Auteur ; Justin R. Serrano, Auteur Année de publication : 2011 Article en page(s) : pp. [044505/1-4] Note générale : Physique Langues : Anglais (eng) Mots-clés : Fermi  relaxation  Electron-electron  scattering  Thermoreflectance Index. décimale : 536 Chaleur. Thermodynamique Résumé : In this work, we examine Fermi relaxation in 20 nm Au films with pump-probe themoreflectance using a thin film, intraband thermoreflectance model. Our results indicate that the Fermi relaxation of a perturbed electron system occurs approximately 1.10±0.05 ps after absorption of a 785 nm, 185 fs laser pulse. This is in agreement with reported values from electron emission experiments but is higher than the Fermi relaxation time determined from previous thermoreflectance measurements. This discrepancy arises due to thermoreflectance modeling and elucidates the importance of the use of a proper thermoreflectance model for thermophysical property determination in pump-probe experiments. DEWEY : 536 ISSN : 0022-1481 En ligne : http://asmedl.aip.org/vsearch/servlet/VerityServlet?KEY=JHTRAO&smode=strresults& [...] [article] Re-examining electron-fermi relaxation in gold films with a nonlinear thermoreflectance model [texte imprimé] / Patrick E. Hopkins, Auteur ; Leslie M. Phinney, Auteur ; Justin R. Serrano, Auteur . - 2011 . - pp. [044505/1-4]. Physique Langues : Anglais (eng) in Journal of heat transfer > Vol. 133 N° 4 (Avril 2011) . - pp. [044505/1-4] Mots-clés : Fermi  relaxation  Electron-electron  scattering  Thermoreflectance Index. décimale : 536 Chaleur. Thermodynamique Résumé : In this work, we examine Fermi relaxation in 20 nm Au films with pump-probe themoreflectance using a thin film, intraband thermoreflectance model. Our results indicate that the Fermi relaxation of a perturbed electron system occurs approximately 1.10±0.05 ps after absorption of a 785 nm, 185 fs laser pulse. This is in agreement with reported values from electron emission experiments but is higher than the Fermi relaxation time determined from previous thermoreflectance measurements. This discrepancy arises due to thermoreflectance modeling and elucidates the importance of the use of a proper thermoreflectance model for thermophysical property determination in pump-probe experiments. DEWEY : 536 ISSN : 0022-1481 En ligne : http://asmedl.aip.org/vsearch/servlet/VerityServlet?KEY=JHTRAO&smode=strresults& [...]