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1. Scalable Modeling of Transient Self-Heating of GaN High-Electron-Mobility Transistors Based on Experimental Measurements

Author

Ali Soltani, Meriem Bouchilaoun, Samuel Graham, Georges Pavlidis, Hassan Maher, Christophe Rodriguez, Adrien Cutivet, Bilal Hassan, Francois Boone, Laboratoire Nanotechnologies Nanosystèmes (LN2 ), Université Grenoble Alpes [2016-2019] (UGA [2016-2019])-École Centrale de Lyon (ECL), Université de Lyon-Université de Lyon-Institut National des Sciences Appliquées de Lyon (INSA Lyon), Université de Lyon-Institut National des Sciences Appliquées (INSA)-Institut National des Sciences Appliquées (INSA)-Université de Sherbrooke (UdeS)-École supérieure de Chimie Physique Electronique de Lyon (CPE)-Centre National de la Recherche Scientifique (CNRS), Institut Interdisciplinaire d'Innovation Technologique [Sherbrooke] (3IT), Université de Sherbrooke (UdeS), Institut d’Électronique, de Microélectronique et de Nanotechnologie - UMR 8520 (IEMN), Centrale Lille-Institut supérieur de l'électronique et du numérique (ISEN)-Université de Valenciennes et du Hainaut-Cambrésis (UVHC)-Université de Lille-Centre National de la Recherche Scientifique (CNRS)-Université Polytechnique Hauts-de-France (UPHF), Puissance - IEMN (PUISSANCE - IEMN), Centrale Lille-Institut supérieur de l'électronique et du numérique (ISEN)-Université de Valenciennes et du Hainaut-Cambrésis (UVHC)-Université de Lille-Centre National de la Recherche Scientifique (CNRS)-Université Polytechnique Hauts-de-France (UPHF)-Centrale Lille-Institut supérieur de l'électronique et du numérique (ISEN)-Université de Valenciennes et du Hainaut-Cambrésis (UVHC)-Université de Lille-Centre National de la Recherche Scientifique (CNRS)-Université Polytechnique Hauts-de-France (UPHF), OMMIC, Université de Sherbrooke (UdeS)-École Centrale de Lyon (ECL), Université de Lyon-Université de Lyon-École Supérieure de Chimie Physique Électronique de Lyon (CPE)-Institut National des Sciences Appliquées de Lyon (INSA Lyon), Université de Lyon-Institut National des Sciences Appliquées (INSA)-Institut National des Sciences Appliquées (INSA)-Centre National de la Recherche Scientifique (CNRS)-Université Grenoble Alpes [2016-2019] (UGA [2016-2019]), Optoélectronique - IEMN (OPTO - IEMN), and This work was supported in part by the Fonds quèbècois de la recherche sur la nature et les technologies (FRQNT) and in part by the Natural Sciences and Engineering Research Council of Canada (NSERC). The review of this paper was arranged by Editor R. Venkatasubramanian

Subjects
Materials science, Thermal resistance, Gallium nitride, High-electron-mobility transistor, 01 natural sciences, Temperature measurement, law.invention, [SPI]Engineering Sciences [physics], chemistry.chemical_compound, gate resistance thermometry (GRT), law, 0103 physical sciences, Thermal, Electrical and Electronic Engineering, ComputingMilieux_MISCELLANEOUS, 010302 applied physics, high-electron-mobilitytransistors (HEMTs), business.industry, Transistor, modeling, Electronic, Optical and Magnetic Materials, chemistry, Gallium nitride (GaN), Logic gate, Optoelectronics, thermoreflectance, Transient (oscillation), business, transient temperature measurement
Abstract

International audience; Abstract:This paper details an extraction procedure to fully model the transient self-heating of transistors from a GaN HEMT technology. Frequency-resolved gate resistance thermometry (f-GRT) is used to extract the thermal impedance of HEMTs with various gate widths. A fully scalable analytical model is developed from the experimental results. In the second stage, transient thermoreflectance imaging (TTI) is used to bring deeper insights into the HEMTs' temperature distribution by individually extracting the transient self-heating of each finger. TTI results are further used to successfully validate the f-GRT results and the modeling of the thermal impedance. Overall, f-GRT is demonstrated to be a fast and robust method for characterizing the transient thermal characteristics of a GaN HEMT. For the first time to the authors' knowledge, a scalable model of the thermal impedance is extracted fully from experimental results.

Published
2019
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2. Mechanical and thermal behavior of natural fiber-polymer composites without compatibilizers

Author

Veikko Sajaniemi, Jouni Paltakaric, Alp Karakoç, Department of Communications and Networking, Paper Converting and Packaging, Department of Bioproducts and Biosystems, Aalto-yliopisto, and Aalto University

Subjects
natural fiber polymer composite, Materials science, pulp, Mechanics of Materials, Mechanical Engineering, Thermal, Polymer composites, compatibilizer, Composite material, Engineering (miscellaneous), Natural fiber, polypropylene, Civil and Structural Engineering
Abstract

The present study aims at understanding the mechanical and thermal properties of natural fibers in a polymer matrix without strong adhesionbetween the two constitutes. For this purpose, four types of pulps, which arerefined and unrefined pine and birch kraft pulps,were used together with polypropylene without any compatibilizer. One constituent pulpbasedand composite pulp fiber-polypropylene handsheets were prepared by standard laboratory sheet preparation method followed by hot pressing process. In addition to these handsheets, pure polypropylene sheets were also formed as the reference. The produced handsheets were testedtodetermine their tensile properties following the ISO 1924-2 standard for paper and board. During these tests, infrared thermal imaging was also carried out with FLIR A655SC thermal camera with frame rate of 200 Hz and thermal resolution of 50 mK so as to investigate the thermal behavior. As a result of the experiments, it was deducedthat the chosen methods produced composites with unsatisfactory properties. In addition, microstructures of the investigated handsheets were analyzed with scanning electronmicroscopy (SEM)indicating theheterogeneous mixing of constituents and existence of material defects, whichwas mainly due to the inherent incompatibility of hydrophilic natural fibers and hydrophobic thermoplastics. The study aims at pavinga way for improved naturalfiber-polymer composite manufacturing methods, a requirement for better understanding the natural fiberand polymer matrix bonding practices.

Published
2019
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