Bibliografie tematiche / HEMT AlN/GaN

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Letteratura scientifica selezionata sul tema "HEMT AlN/GaN"

Autore: Grafiati
Pubblicato: 1 marzo 2025

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Articoli di riviste sul tema "HEMT AlN/GaN"

1

Chiu, Hsien-Chin, Chia-Hao Liu, Chong-Rong Huang, Chi-Chuan Chiu, Hsiang-Chun Wang, Hsuan-Ling Kao, Shinn-Yn Lin e Feng-Tso Chien. "Normally-Off p-GaN Gated AlGaN/GaN MIS-HEMTs with ALD-Grown Al2O3/AlN Composite Gate Insulator". Membranes 11, n. 10 (23 settembre 2021): 727. http://dx.doi.org/10.3390/membranes11100727.

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A metal–insulator–semiconductor p-type GaN gate high-electron-mobility transistor (MIS-HEMT) with an Al2O3/AlN gate insulator layer deposited through atomic layer deposition was investigated. A favorable interface was observed between the selected insulator, atomic layer deposition–grown AlN, and GaN. A conventional p-type enhancement-mode GaN device without an Al2O3/AlN layer, known as a Schottky gate (SG) p-GaN HEMT, was also fabricated for comparison. Because of the presence of the Al2O3/AlN layer, the gate leakage and threshold voltage of the MIS-HEMT improved more than those of the SG-HEMT did. Additionally, a high turn-on voltage was obtained. The MIS-HEMT was shown to be reliable with a long lifetime. Hence, growing a high-quality Al2O3/AlN layer in an HEMT can help realize a high-performance enhancement-mode transistor with high stability, a large gate swing region, and high reliability.
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2

Tsai, Jung-Hui, Jing-Shiuan Niu, Xin-Yi Huang e Wen-Chau Liu. "Comparative Investigation of AlGaN/AlN/GaN High Electron Mobility Transistors with Pd/GaN and Pd/Al2O3/GaN Gate Structures". Science of Advanced Materials 13, n. 2 (1 febbraio 2021): 289–93. http://dx.doi.org/10.1166/sam.2021.3856.

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In this article, the electrical characteristics of Al0.28Ga0.72 N/AlN/GaN metal-oxide-semiconductor high electron mobility transistor (MOS-HEMT) with a 20-nm-thick Al2O3 layer by using radio-frequency sputtering as the gate dielectric layer are compared to the conventional metal-semiconductor HEMT (MS-HEMT) with Pd/GaN gate structure. For the insertion of the Al2O3 layer, the energy band near the AlN/GaN heterojunction is lifted slightly up and the 2DEG at the heterojunction is reduced to shift the threshold voltage to the right side. Experimental results exhibits that though the maximum drain current decreases about 6.5%, the maximum transconductance increases of 9%, and the gate leakage current significantly reduces about five orders of magnitude for the MOS-HEMT than the MS-HEMT.
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Shrestha, Niraj Man, Yuen Yee Wang, Yiming Li e E. Y. Chang. "Simulation Study of AlN Spacer Layer Thickness on AlGaN/GaN HEMT". Himalayan Physics 4 (22 dicembre 2013): 14–17. http://dx.doi.org/10.3126/hj.v4i0.9419.

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High electron mobility transistor (HEMT)Two-dimensional electron gas (2DEG) formed at AlGaN/GaN interface is a critical part to tune the characteristic of AlGaN/GaN HEMT devices. Introduction of AlN spacer layer in between AlGaN and GaN layer is one of the way to improve 2DEG density, mobility, and drain current. Carrier concentration, mobility and conduction band offset for different spacer layer thickness was simulated by using Silvaco simulation tool. Our device simulations showed that carrier concentration, mobility are enhance on introduction of AlN spacer layer in HEMT. In addition, carrier properties of HEMT also depend on thickness of spacer layer. Our simulation showed that the mobility of 2DEG attains its maximum value at the 0.5 nm thick AlN layer but carrier concentration increases with spacer thickness. Finally, drain current increases with increasing spacer layer thickness and reach maximum value at 1.2nm thick spacer layer.The Himalayan Physics Vol. 4, No. 4, 2013 Page: 14-17 Uploaded date: 12/22/2013
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Yamaoka, Yuya, Kazuhiro Ito, Akinori Ubukata, Toshiya Tabuchi, Koh Matsumoto e Takashi Egawa. "Effect of the formation temperature of the AlN/Si interface on the vertical-direction breakdown voltages of AlGaN/GaN HEMTs on Si substrates". MRS Advances 1, n. 50 (2016): 3415–20. http://dx.doi.org/10.1557/adv.2016.431.

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ABSTRACT In this study, the initial AlN layer and the vertical-direction breakdown voltage (VDBV) of AlGaN/GaN high-electron-mobility transistors (HEMTs) were characterized. Prior to the formation of the interface between the AlN layer and the Si substrate, only trimethylaluminum (TMA) was introduced without ammonia to control the crystal quality of initial AlN layer (TMA preflow). HEMT structures were simultaneously grown on identical AlN layers on Si substrates (AlN/Si templates) grown using different TMA preflow temperatures. The density of screw- or mixed-type dislocations in the initial AlN layer decreased as the TMA preflow temperature increased. Further, the VDBV of the HEMT structure increased as the TMA preflow temperature increased. It is supposed that the screw- or mixed-type dislocations are the possible source of the vertical leakage current in the HEMT structures. The improvement in the crystal quality of the initial AlN layer affects the increase in the VDBV of the AlGaN/GaN HEMTs on Si substrates.
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Çörekçi, S., D. Usanmaz, Z. Tekeli, M. Çakmak, S. Özçelik e E. Özbay. "Surface Morphology of Al0.3Ga0.7N/Al2O3-High Electron Mobility Transistor Structure". Journal of Nanoscience and Nanotechnology 8, n. 2 (1 febbraio 2008): 640–44. http://dx.doi.org/10.1166/jnn.2008.a181.

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We present surface properties of buffer films (AlN and GaN) and Al0.3Ga0.7N/Al2O3-High Electron Mobility Transistor (HEMT) structures with/without AlN interlayer grown on High Temperature (HT)-AlN buffer/Al2O3 substrate and Al2O3 substrate. We have found that the GaN surface morphology is step-flow in character and the density of dislocations was about 108–109 cm−2. The AFM measurements also exhibited that the presence of atomic steps with large lateral step dimension and the surface of samples was smooth. The lateral step sizes are in the range of 100–250 nm. The typical rms values of HEMT structures were found as 0.27, 0.30, and 0.70 nm. HT-AlN buffer layer can have a significant impact on the surface morphology of Al0.3Ga0.7N/Al2O3-HEMT structures.
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Hong, Kuo-Bin, Chun-Yen Peng, Wei-Cheng Lin, Kuan-Lun Chen, Shih-Chen Chen, Hao-Chung Kuo, Edward Yi Chang e Chun-Hsiung Lin. "Thermal Analysis of Flip-Chip Bonding Designs for GaN Power HEMTs with an On-Chip Heat-Spreading Layer". Micromachines 14, n. 3 (23 febbraio 2023): 519. http://dx.doi.org/10.3390/mi14030519.

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In this work, we demonstrated the thermal analysis of different flip-chip bonding designs for high power GaN HEMT developed for power electronics applications, such as power converters or photonic driver applications, with large gate periphery and chip size, as well as an Au metal heat-spreading layer deposited on top of a planarized dielectric/passivation layer above the active region. The Au bump patterns can be designed with high flexibility to provide more efficient heat dissipation from the large GaN HEMT chips to an AlN package substrate heat sink with no constraint in the alignment between the HEMT cells and the thermal conduction bumps. Steady-state thermal simulations were conducted to study the channel temperatures of GaN HEMTs with various Au bump patterns at different levels of current and voltage loadings, and the results were compared with the conventional face-up GaN die bonding on an AlN package substrate. The simulations were started from a single finger isolated HEMT cell and then extended to multiple fingers HEMT cells (total gate width > 40 mm) to investigate the “thermal cross-talk” effect from neighboring devices. Thermal analysis of the GaN HEMT under pulse operation was also performed to better reflect the actual conditions in power conversion or pulsed laser driver applications. Our analysis provides a combinational assessment of power GaN HEMT dies under a working condition (e.g., 1MHz, 25% duty cycle) with different flip chip packaging schemes. The analysis indicated that the channel temperature rise (∆T) of a HEMT cell in operation can be reduced by 44~46% by changing from face-up die bonding to a flip-chip bonding scheme with an optimized bump pattern design.
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Gusev, A. S., A. O. Sultanov, A. V. Katkov, S. M. Ryndya, N. V. Siglovaya, A. N. Klochkov, R. V. Ryzhuk, N. I. Kargin e D. P. Borisenko. "Carrier Scattering Analysis in AlN/GaN HEMT Heterostructures with an Ultrathin AlN Barrier". Mikroèlektronika 53, n. 3 (27 ottobre 2024): 265–73. http://dx.doi.org/10.31857/s0544126924030086.

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Experimental AlN/GaN heterostructures (HSs) with an ultrathin AlN barrier were obtained using molecular beam epitaxy with plasma activation of nitrogen. The layer resistance of the optimized structures was less than 230 Ω/¨. The scattering processes that limit the mobility of two-dimensional electron gas in undoped AlN/GaN HSs with an ultrathin AlN barrier have been studied. It is shown that in the ns range characteristic of AlN/GaN HEMT HSs (ns 1 × 1013 cm–2), a noticeable contribution to the scattering of charge carriers is made by the roughness of the heterointerface.
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Shen, L., S. Heikman, B. Moran, R. Coffie, N. Q. Zhang, D. Buttari, I. P. Smorchkova, S. Keller, S. P. DenBaars e U. K. Mishra. "AlGaN/AlN/GaN high-power microwave HEMT". IEEE Electron Device Letters 22, n. 10 (ottobre 2001): 457–59. http://dx.doi.org/10.1109/55.954910.

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9

Wang, X. H., X. L. Wang, C. Feng, C. B. Yang, B. Z. Wang, J. X. Ran, H. L. Xiao, C. M. Wang e J. X. Wang. "Hydrogen sensors based on AlGaN/AlN/GaN HEMT". Microelectronics Journal 39, n. 1 (gennaio 2008): 20–23. http://dx.doi.org/10.1016/j.mejo.2007.10.022.

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Popok, V. N., T. S. Aunsborg, R. H. Godiksen, P. K. Kristensen, R. R. Juluri, P. Caban e K. Pedersen. "Structural Characterization of Movpe Grown Algan/Gan for Hemt Formation". REVIEWS ON ADVANCED MATERIALS SCIENCE 57, n. 1 (1 giugno 2018): 72–81. http://dx.doi.org/10.1515/rams-2018-0049.

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Abstract Results on structural, compositional, optical and electrical characterization of MOVPE grown AlGaN/GaN heterostructures with focus on understanding how the AlN buffer synthesis affects the top films are reported. The study demonstrates very good correlation between different methods providing a platform for reliable estimation of crystalline quality of the AlGaN/GaN structures and related to that electrical performance which is found to be significantly affected by threading dislocations (TD): higher TD density reduces the electron mobility while the charge carrier concentration is found to be largely unchanged. The attempt to vary the ammonia flow during the AlN synthesis is found not to affect the film composition and dislocation densities in the following heterostructures. An unusual phenomenon of considerable diffusion of Ga from the GaN film into the AlN buffer is found in all samples under the study. The obtained results are an important step in optimization of AlGaN/GaN growth towards the formation of good quality HEMT structures on sapphire and transfer of technology to Si substrates by providing clear understanding of the role of synthesis parameter on structure and composition of the films.
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Più fonti

Tesi sul tema "HEMT AlN/GaN"

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Lundskog, Anders. "Characterization of AlGaN HEMT structures". Thesis, Linköping University, The Department of Physics, Chemistry and Biology, 2007. http://urn.kb.se/resolve?urn=urn:nbn:se:liu:diva-9729.

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Abstract (sommario):

During the last decade, AlGaN High Electron Mobility Transistors (HEMTs) have been intensively studied because their fundamental electrical properties make them attractive for highpower microwave device applications. Despite much progress, AlGaN HEMTs are far from fully understood and judged by the number of published papers the understanding of advanced structures is even poorer. This work is an exploration of the electrical and structural properties of advanced HEMT structure containing AlN exclusionlayer and double heterojunctions. These small modifications had great impact on the electrical properties.

In this work, AlGaN HEMT structures grown on SiC substrates by a hot-wall MOCVD have been characterized for their properties using optical microscopy, scanning electron microscopy, transmission electron microscopy, capacitance/voltage, eddy-current resistivity, and by homebuilt epi-thickness mapping equipment.

A high electron mobility of 1700 [cm2/Vs] was achieved in an AlN exclusion-layer HEMT. A similar electron mobility of 1650 [cm2/Vs] was achieved in a combination of a double heterojunction and exclusion-layer structure. The samples had approximately the same electron mobility but with a great difference: the exclusion-layer version gave a sheet carrier density of 1.58*1013 [electrons/cm2] while the combination of double heterojunction and exclusion-layer gave 1.07*1013 [electrons/cm2]. A second 2DEG was observed in most structures, but not all, but was not stable with time.

The structures we grew during this work were also simulated using a one-dimensional Poisson-Schrödinger solver and the simulated electron densities were in fairly good agreement with the experimentally obtained. III-nitride materials, the CVD concept, and the onedimensional solver are shortly explained.

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Said, Nasri. "Evaluation de la robustesse des technologies HEMTs GaN à barrière AlN ultrafine pour l'amplification de puissance au-delà de la bande Ka". Electronic Thesis or Diss., Bordeaux, 2024. http://www.theses.fr/2024BORD0425.

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La filière GaN est stratégique pour l'Union Européenne car elle permet d'améliorer la puissance et le rendement des systèmes radar et de télécommunication, notamment dans les bandes S à Ka (jusqu'à 30 GHz). Pour répondre aux besoins des futures applications, telles que la 5G et les systèmes militaires, le développement des technologies GaN vise à augmenter les fréquences jusqu'aux ondes millimétriques. Cela nécessite d'optimiser l'épitaxie et la réduction de la longueur de grille à moins de 150 nm, ainsi que l'utilisation de barrières ultrafines (<10 nm) pour éviter les effets de canaux courts. La substitution de la barrière AlGaN par du AlN représente une solution pour maintenir de bonnes performances tout en miniaturisant les composants. Dans ces travaux de thèse, plusieurs variantes technologiques à barrière AlN ultrafine (3 nm) sur des canaux GaN non-dopés de différentes épaisseurs, développées par le laboratoire IEMN sont étudiés. L'évaluation des performances et de la robustesse de ces technologies, cruciale pour leur qualification et utilisation dans des missions à long-terme, sont ainsi menées en mode DC et RF afin de définir les zones de sécurité de fonctionnement (SOA) et d’identifier les mécanismes de dégradation.La campagne de caractérisation DC et pulsée a révélé une faible dispersion des composants après leur stabilisation électrique, reflétant une bonne maîtrise technologique : ceci permet par ailleurs des études statistiques et des analyses génériques plus pertinentes sur l’ensemble des lots de composants étudiés. L'analyse de la sensibilité des dispositifs à des températures allant jusqu'à 200°C a prouvé la forte stabilité thermique des performances en mode diode et transistor, en suivant les indicateurs paramétriques représentatifs des modèles électriques des composants (courants de saturation et courants de fuite, tension de seuil, taux de retard aux commandes entrée sortie, …). L’ajout d’une barrière arrière AlGaN sur une couche tampon moyennement dopée C a réglé le compromis entre confinement des électrons et densités de pièges. Les tests de vieillissement accéléré en mode DC à différents points de polarisation et en mode RF par paliers de puissance d’entrée ont montré que la barrière arrière AlGaN confère une meilleure stabilité des courants de fuite et des courbes I(V) statiques, une réduction des effets de piégeage et d'auto-échauffement, ainsi qu'une extension de la SOA-DC opérationnelle. Les tests de vieillissement accéléré en mode dynamique à 10 GHz sur des HEMTs avec différents espacements grille-drain ont montré que la SOA-RF ne dépend pas de cet espacement, mais plutôt de la capacité de la grille à supporter des signaux RF élevés, avant dégradation brutale de cette dernière. En utilisant une méthode de modélisation non linéaire originale, prenant en compte le phénomène d'auto-polarisation, les dispositifs avec barrière AlGaN se sont révélés plus robustes également en RF. Cela se traduit par leur compression plus tardive de gain, allant jusqu’à +10dB et sans dégradation électrique ainsi que structurelle apparente (observée par photoluminescence). Indépendamment de la variante AlN/GaN, le mécanisme de dégradation en stress RF correspond au claquage abrupt de la grille Schottky conduisant à sa défaillance. Ces résultats prouvent que les composants sont plus sensibles aux conditions de polarisation DC qu’au niveau de signal RF injecté [...]
The GaN industry is strategic for the European Union because it enhances the power and efficiency of radar and telecommunication systems, especially in the S to Ka bands (up to 30 GHz). To meet the needs of future applications such as 5G and military systems, GaN technology development aims to increase frequencies to the millimeter-wave range. This requires optimizing epitaxy and reducing the gate length to less than 150 nm, as well as using ultrathin barriers (<10 nm) to avoid short-channel effects. Replacing the AlGaN barrier with AlN is a solution to maintain good performance while miniaturizing devices. In this thesis, several technological variants with an ultrathin AlN barrier (3 nm) on undoped GaN channels of various thicknesses, developed by the IEMN laboratory, are studied. The evaluation of the performance and robustness of these technologies, crucial for their qualification and use in long-term profil missions, is conducted in both DC and RF modes to define the safe operating areas (SOA) and identify degradation mechanisms.The DC and pulsed characterization campaign revealed low component dispersion after electrical stabilization, reflecting good technological control. This also allows for more relevant statistical studies and generic analyses across all component batches studied. The sensitivity analysis of the devices at temperatures up to 200°C demonstrated strong thermal stability in diode and transistor modes, following parametric indicators representative of the electrical models of the components (saturation currents and leakage currents, threshold voltage, gate and drain lags rates, ...). The addition of a AlGaN back-barrier on a moderately C-doped buffer layer resolved the trade-off between electron confinement and trap densities. Accelerated aging tests in DC mode at various biasing conditions and in RF mode by input power steps showed that the AlGaN back-barrier provides better stability in leakage currents and static I(V) curves, reduces trapping and self-heating effects, and extends the operational DC-SOA.Dynamic accelerated aging tests at 10 GHz on HEMTs with different gate-drain spacings showed that the RF-SOA does not depend on this spacing but rather on the gate's ability to withstand high RF signals before abrupt degradation occurs. Using an original nonlinear modeling method that considers the self-biasing phenomenon, devices with the AlGaN back-barrier proved to be more robust in RF as well. This is reflected in their later gain compression, up to +10 dB, without apparent electrical or structural degradation (as observed by photoluminescence). Regardless of the AlN/GaN variant, the RF stress degradation mechanism corresponds to the abrupt breakdown of the Schottky gate, leading to its failure. These results indicate that the components are more sensitive to DC bias conditions than to the level of injected RF signals [...]
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3

Bradley, Shawn Todd. "Investigation of AlGaN films and nickel/AlGaN Schottky diodes using depth-dependent cathodoluminescence spectroscopy and secondary ion mass spectrometry". Columbus, Ohio : Ohio State University, 2004. http://rave.ohiolink.edu/etdc/view?acc%5Fnum=osu1078329692.

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Thesis (Ph. D.)--Ohio State University, 2004.
Title from first page of PDF file. Document formatted into pages; contains xxii, 182 p.; also includes graphics (some col.). Includes abstract and vita. Advisor: Leonard J. Brillson, Dept. of Electrical Engineering. Includes bibliographical references (p. 173-182).
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4

Taking, Sanna. "AlN/GaN MOS-HEMTs technology". Thesis, University of Glasgow, 2012. http://theses.gla.ac.uk/3356/.

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The ever increasing demand for higher power devices at higher frequencies has prompted much research recently into the aluminium nitride/gallium nitride high electron mobility transistors (AlN/GaN HEMTs) in response to theoretical predictions of higher performance devices. Despite having superior material properties such as higher two-dimensional electron gas (2DEG) densities and larger breakdown field as compared to the conventional aluminium gallium nitride (AlGaN)/GaN HEMTs, the AlN/GaN devices suffer from surface sensitivity, high leakage currents and high Ohmic contact resistances. Having very thin AlN barrier layer of ∼ 3 nm makes the epilayers very sensitive to liquids coming in contact with the surface. Exposure to any chemical solutions during device processing degrades the surface properties, resulting in poor device performance. To overcome the problems, a protective layer is employed during fabrication of AlN/GaN-based devices. However, in the presence of the protective/passivation layers, formation of low Ohmic resistance source and drain contact becomes even more difficult. In this work, thermally grown aluminium oxide (Al2O3) was used as a gate di- electric and surface passivation for AlN/GaN metal-oxide-semiconductor (MOS)-HEMTs. Most importantly, the Al2O3 acts as a protection layer during device processing. The developed technique allows for a simple and effective wet etching optimisation using 16H3PO4:HNO3:2H2O solution to remove Al from the Ohmic contact regions prior to the formation of Al2O3 and Ohmic metallisation. Low Ohmic contact resistance (0.76Ω.mm) as well as low sheet resistance (318Ω/square) were obtained after optimisation. Significant reduction in the gate leakage currents was observed when employing an additional layer of thermally grown Al2O3 on the mesa sidewalls, particularly in the region where the gate metallisation overlaps with the exposed channel edge. A high peak current ∼1.5 A/mm at VGS=+3 V and a current-gain cutoff frequency, fT , and maximum oscillation frequency, fMAX , of 50 GHz and 40 GHz, respectively, were obtained for a device with 0.2 μm gate length and 100 μm gate width. The measured breakdown voltage, VBR, of a two-finger MOS-HEMT with 0.5μm gate length and 100 μm gate width was 58 V. Additionally, an approach based on an accurate estimate of all the small-signal equivalent circuit elements followed by optimisation of these to get the actual element values was also developed for AlN/GaN MOS-HEMTs. The extracted element values provide feedback for further device process optimisation. The achieved results indicate the suitability of thermally grown Al2O3 for AlN/GaN-based MOS-HEMT technology for future high frequency power applications.
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John, Dylan Boone. "Atomistic Modeling of AlN/GaN HEMTs for Applications in Harsh Environments". OpenSIUC, 2011. https://opensiuc.lib.siu.edu/theses/572.

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Abstract (sommario):
AlN/GaN high-electron mobility transistors (HEMT) are subject to internal structural and electrostatic fields originating mainly from: (i) the fundamental crystal atomicity and the interface discontinuity between dissimilar materials, (ii) atomistic strain, (iii) piezoelectricity, and (iv) spontaneous polarization (pyroelectricity). In this thesis, through numerical simulations, we have studied the origin and effects of these competing internal fields on the electrostatics and the I-V characteristic of scaled nitride HEMT structures. It is shown that strain in these devices is asymmetric and long-ranged (demanding simulations using millions of atoms). The resulting piezoelectric polarization is arge and atomistic in nature. However, the pyroelectric potential is significantly larger than the piezoelectric counterpart and opposes the latter at the InN/GaN interface as opposed to AlGas which only produces a piezoelectric potential. The polarization induced charge density is computed using a three-dimensional Poisson solver and shown to be strongly dependent on the thickness of the AlN barrier layer. This finding has been validated using available experimental data. We have also demonstrated that the olarization fields alone can induce channel carriers at zero external bias and lead to a significant increase in the ON current.
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Abou, Daher Mahmoud. "Réalisation et optimisation de transistors HEMT GaN forte puissance et haute fréquence par technologie de transfert de couches sur substrat hôte". Thesis, Toulouse 3, 2020. http://www.theses.fr/2020TOU30046.

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Abstract (sommario):
Le marché des télécommunications tire profit des nouvelles technologies Nitrures qui sont en véritable rupture de performances par rapport aux technologies traditionnellement utilisées. Les recherches actuelles ouvrent de nombreuses pistes et solutions alternatives afin de couvrir des contraintes parfois antagonistes de coût, de performances et/ou de fiabilité. La plupart des HEMTs AlGaN / GaN est fabriquée sur un substrat de silicium hautement résistif à faible coût ou sur substrat SiC beaucoup plus onéreux et sensible du point de vue approvisionnement. Les contraintes de performances électriques requises lors de l'intégration de ces technologies dans les systèmes radars, les satellites et en télécommunication rendent les HEMTs très dépendants au paramètre de température de fonctionnement, essentiellement liée à la forte puissance dissipée lors du transfert d'énergie statique/dynamique. En effet, ces composants sont capables de générer des densités de puissance élevées dans le domaine des hyperfréquences. Aussi, l'augmentation de la fréquence de fonctionnement s'accompagne d'une augmentation de la puissance dissipée engendrant le phénomène d'auto-échauffement qui influe sur les performances des composants (ID,max,ft,fmax...). Dans ce contexte, plusieurs solutions ont déjà été proposées dans la littérature (utilisations des substrats composites, passivation des composants, etc...). De plus, la technologie de transfert des HEMTs d'un substrat de croissance initial vers un substrat hôte de bonne conductivité thermique (tel que le substrat de diamant) est une solution prometteuse, encore peu détaillée à ce jour. L'objectif de ce travail de thèse est d'améliorer la dissipation thermique et donc les performances et la fiabilité des transistors HEMT hautes fréquences en utilisant la technologie de transfert de couche. Les hétérostructures AlGaN/GaN sont développées sur substrat de silicium par MOCVD au CHREA. Après la fabrication des HEMTs sur substrat de silicium au sein du laboratoire IEMN, les composants (pour lesquels le substrat silicium a été retiré) sont transférés sur un substrat de diamant. Ce transfert est obtenu grâce à un collage par thermocompression de couche d'AlN pulvérisées sur chaque surface à assembler (face arrière des transistors et substrat diamant). Le procédé de transfert développé n'a pas endommagé la fonctionnalité des transistors HEMTs AlGaN/GaN à faible longueur de grille (Lg = 80 nm). Les transistors de développement 2x35 µm transférés sur diamant présentent un courant ID,max = 710 mA.mm-1, une fréquence de coupure ft de 85GHz et une fréquence d'oscillation fmax de 144GHz. Toutefois, la technique de transfert mérite des phases d'optimisations (notamment pour diminuer l'épaisseur et améliorer la qualité cristalline et la conductivité thermique des couches d'AlN) afin de mieux satisfaire aux contraintes de réduction de résistance thermique de cette couche d'assemblage et ainsi limiter le phénomène d'auto-échauffement relevé à l'issue de ces travaux de thèse
Wireless telecommunication market largely benefits from new nitride technologies, which reach outstanding performance compared with traditional technologies. Current research is opening up many new strategies and alternative solutions to address simultaneously antagonist considerations such as cost, performances and/or reliability. Most AlGaN / GaN HEMTs are fabricated on a low cost, highly resistive silicon substrate or on a much more expensive and supply sensitive SiC substrate. However, the electrical performance constraints required when these technologies are integrating into radar systems, satellites and in telecommunications systems make them dependent to the operating temperature parameter, mainly linked to the high power dissipation during static/dynamic energy transfer. Indeed, these components are capable of generating high power densities in the microwave range. However, the operating frequency increase leads an increase of the power dissipation, generating the self-heating phenomenon which influences the devices performance (ID,max,ft,fmax...). In this context, several solutions were already proposed in the literature (use of composite substrates, passivation of devices, etc.). Furthermore, the layer transfer technology to report HEMTs from growth substrate onto a host substrate with a good thermal conductivity (such as diamond substrate) is a promising solution, still poorly detailed to date. The objective of this thesis work is to improve the heat dissipation and thus the performance and reliability of high-frequency HEMT transistors by using a layer transfer technology. AlGaN / GaN heterostructures are grown on a silicon substrate by MOCVD at CHREA. After the fabrication of HEMTs on a silicon substrate, AlGaN / GaN devices (for which the silicon substrate has been removed) are transferred onto a CVD diamond substrate. This transfer is obtained by thermocompression bonding of sputtered AlN layers on each surface to be assembled (backside of the transistors and diamond substrate). This transfer process has not damaged the functionality of the transistors with short gate length (Lg = 80 nm). The AlGaN/GaN HEMTs with a 2x35 µm development transferred onto diamond of feature a current ID,max = 710 mA.mm-1, a cutoff frequency ft of 85GHz and an oscillation frequency fmax of 144GHz. However, this transfer technique requires optimization phases (especially to reduce thickness and improve the crystalline quality and thermal conductivity of AlN layers) in order to reduce the thermal resistance of this adhesion layer and to limit the self-heating phenomenon noted at the end of this thesis work
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Hung, Ting-Hsiang. "Novel High-k Dielectric Enhanced III-Nitride Devices". The Ohio State University, 2015. http://rave.ohiolink.edu/etdc/view?acc_num=osu1437684419.

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Kim, Samuel H. "Addressing thermal and environmental reliability in GaN based high electron mobility transistors". Thesis, Georgia Institute of Technology, 2014. http://hdl.handle.net/1853/52244.

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AlGaN/GaN high electron mobility transistors (HEMTs) have appeared as attractive candidates for high power, high frequency, and high temperature operation at microwave frequencies. In particular, these devices are being considered for use in the area of high RF power for microwave and millimeter wave communications transmitter applications at frequencies greater than 100 GHz and at temperatures greater than about 150 °C. However, there are concerns regarding the reliability of AlGaN/GaN HEMTs. First of all, thermal reliability is the chief concern since high channel temperatures significantly affect the lifetime of the devices. Therefore, it is necessary to find the solutions to decrease the temperature of AlGaN/GaN HEMTs. In this study, we explored the methods to reduce the channel temperature via high thermal conductivity diamond as substrates of GaN. Experimental verification of AlGaN/GaN HEMTs on diamond substrates was performed using micro-Raman spectroscopy, and investigation of the design space for devices was conducted using finite element analysis as well. In addition to the thermal impact on reliability, environmental effects can also play a role in device degradation. Using high density and pinhole free films deposited using atomic layer deposition, we also explore the use of ultra-thin barrier films for the protection of AlGaN/GaN HEMTs in high humidity and high temperature environments. The results show that it is possible to protect the devices from the effects of moisture under high negative gate bias stress testing, whereas devices, which were unprotected, failed under the same bias stress conditions. Thus, the use of the atomic layer deposition (ALD) coatings may provide added benefits in the protection and packaging of AlGaN/GaN HEMTs.
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Le, roux Frédéric. "Développement de procédés de gravure plasma sans dommage pour l'électronique de puissance à base de GaN". Thesis, Université Grenoble Alpes, 2020. http://www.theses.fr/2020GRALT017.

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En électronique de puissance, le GaN est devenu un matériau de choix : il répond à des enjeux de haute performance énergétique, tout en favorisant une compacité et une légèreté des composants. Lors de la fabrication de dispositifs de puissance basés sur une hétérostructure AlGaN/GaN, la gravure plasma induit des dégradations dans le matériau et réduit les propriétés électroniques des composants notamment les diodes et les HEMT (High Electron Mobility Transistors). Ces travaux de thèses se sont focalisés sur l’étude de ces dégradations et proposent des procédés de gravure industrialisables qui diminuent l’impact de ces plasmas. Nous nous sommes concentrés dans un premier temps sur les mécanismes de dégradation intervenant pendant la gravure du SiN avec arrêt sur AlGaN, en fonction de différents paramètres plasma. Les caractérisations électriques et physico-chimiques (notamment l’XPS) ont permis de mettre en avant différents mécanismes de dégradations et d’en proposer un modèle synthétique. Nous avons identifié deux facteurs principaux de dégradation électrique : d’une part, le bombardement ionique énergétique qui modifie les stœchiométries de surface, favorise l’implantation de contaminants, perturbe la qualité cristalline de la maille et provoque la pulvérisation de l’AlGaN. Un seuil en énergie, sous lequel les dégradations restent limitées, a cependant été démontré et éprouvé. Le second facteur identifié est l’épaisseur modifiée. Plus l’épaisseur modifiée est importante, plus elle a une influence sur le canal électronique et ses propriétés. Cette épaisseur peut être augmentée par une haute énergie de bombardement ou par l’utilisation d’éléments légers qui s’implantent en profondeur dans l’AlGaN. Dans un second temps, ces résultats ont servi de cadre pour le développement de procédés innovants afin de limiter l’endommagement lors de la gravure GaN. Nous avons étudié trois procédés cycliques de type ALE : O2-BCl3, Cl2-Ar et Cl2-He. Leurs études ont permis de mettre en évidence leurs différentes caractéristiques d’autolimitations et de sélectivités ainsi que de proposer des modèles de mécanismes de gravure. La caractérisation et la comparaison avec les procédés standards ont soulignés leurs performances et notamment leurs capacités à diminuer les dégradations électriques induites pendant la gravure
In power electronics, GaN has become a material of choice: it meets the challenges of high energy performance, while promoting compactness and lightness of the components. When manufacturing power devices based on an AlGaN / GaN heterostructure, plasma etching induces degradations in the material and reduces the electronic properties of the components, in particular diodes and HEMT (High Electron Mobility Transistors). These thesis works focused on the study of these degradations and proposes industrializable etching processes which reduce these plasma impacts. We first focused on the degradation mechanisms involved during the etching of SiN with stop on AlGaN, according to different plasma parameters. The electrical and physicochemical characterizations (in particular the XPS) made it possible to highlight various degradation mechanisms and to propose a synthetic model. We have identified two main factors of electrical degradation: the first one is the energy ion bombardment which modifies the surface stoichiometries, favors the implantation of contaminants, disturbs the crystal quality of the lattice and causes the sputtering of AlGaN. An energy threshold, below which degradations remain limited, has however been demonstrated and tested. The second factor identified is the modified thickness. The greater the modified thickness, the more it has an influence on the electronic channel and its properties. This thickness can be increased by high bombardment energy or by the use of light elements which are deeply implanted in AlGaN. These results then served as a framework for the development of innovative processes in order to limit the damage during GaN etching. We studied three cyclic processes of the ALE type: O2-BCl3, Cl2-Ar and Cl2-He. These studies made it possible to highlight their different self-limiting and selectivity characteristics as well as to propose etching mechanisms models. Characterization and comparison with standard processes have highlighted their performance and in particular their ability to reduce the electrical degradation induced during etching
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Lee, Yuan-Jyun, e 李元鈞. "Optimization of GaN and AlN epilayer for HEMT application". Thesis, 2018. http://ndltd.ncl.edu.tw/handle/m3an56.

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碩士
國立交通大學
電子物理系所
106
GaN, Al1-xGaxN, and AlN epilayers were grown by molecular beam epitaxy system (MBE). The in situ reflection high-energy electron diffraction (RHEED) measurements were used to find the best growth conditions of substrate temperature and element flux ratio. The optical properties and surface morphology were analyzed by photoluminescence (PL), cathodoluminescence (CL), scanning electron microscopy (SEM) and atomic force microscopy (AFM). Moreover, the electrical properties of two dimensional electron gas (2DEG) of AlN/GaN heterostructure were investigated by the Hall measurements. By the control of substrate temperature and Ga/N ratio, the luminescence signal from Ga vacancy could be suppressed and a better surface roughness about 0.4 nm for GaN was achieved. In the case of Al1-xGaxN growth, the substrate temperature was fixed at 740 oC for high Al composition samples. By using the migration enhanced epitaxy (MEE) for the interface expitaxy of AlN/GaN heterostructure, the decomposition of GaN channel layer can be significantly suppressed. The raising substrate temperature to 740 oC enhances migration of the AlN to fill the surface pits. It improves the electron mobility up to 988 (cm2/V•s) in 2DEG.
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Libri sul tema "HEMT AlN/GaN"

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Ponzanesi, Sandra, Kathrin Thiele, Eva Midden, Domitilla Olivieri e Trude Oorschot. Transities in kunst, cultuur en politiek. Nieuwe Prinsengracht 89 1018 VR Amsterdam Nederland: Amsterdam University Press, 2023. http://dx.doi.org/10.5117/9789048560110.

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In deze bundel staat de rol van kunst, cultuur en politiek bij transities en de strijd voor sociale rechtvaardigheid centraal. Soms zijn deze transities traumatische en gewelddadige processen zoals in het geval van Zuid-Afrika na de apartheid. In andere gevallen, zoals in Europa, gaat het om langdurige geschiedenissen die verband hebben met kolonialisme, de holocaust en totalitarisme. De auteurs verkennen intersectionele vraagstukken van transitie en sociale verandering in samenhang met bredere debatten over de rol van democratie, burgerschap en mensenrechten. Ze gaan daarbij een dialoog aan met het werk van feministische wetenschapper Rosemarie Buikema.
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Velberg, Joey. Weg met mannelijkheid. Nieuwe Prinsengracht 89 1018 VR Amsterdam Nederland: Amsterdam University Press, 2024. http://dx.doi.org/10.5117/9789464563054.

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Mannelijkheid is aan verandering toe. Academisch werk over de maatschappelijke noodzaak hiervan is in toenemende mate aanwezig. Maar hoe zit het met ervaringsverhalen van mannen die zichzelf en hun man-zijn vernieuwen? Welke uitdagingen komen zij tegen? En hoe hebben zij een nieuwe vorm van man- zijn omarmd? Weg met mannelijkheid vertelt het persoonlijke verhaal van deze transformatie. Joey Velberg neemt je mee naar momenten die bepalend zijn geweest voor zijn ontwikkeling en laat zien hoe thema’s als identiteit, seksualiteit, werk en familie hierbij een rol hebben gespeeld. Ga mee op reis in dit openhartige boek en vind, net als Joey, hoe je als man meer mens kan zijn. Zodat jij je plek kan innemen in de maatschappij van nu.
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Sherwood, Dennis, e Paul Dalby. Temperature and heat. Oxford University Press, 2018. http://dx.doi.org/10.1093/oso/9780198782957.003.0003.

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Concepts of temperature, temperature scales and temperature measurement. The ideal gas law, Dalton’s law of partial pressure. Assumptions underlying the ideal gas, and distinction between ideal and real gases. Introduction to equations-of-state such as the van der Waals, Dieterici, Berthelot and virial equations, which describe real gases. Concept of heat, and distinction between heat and temperature. Experiments of Rumford and Joule, and the principle of the conservation of energy. Units of measurement for heat. Heat as a path function. Flow of heat down a temperature gradient as an irreversible and unidirectional process. ‘Zeroth’ Law of Thermodynamics. Definitions of isolated, closed and open systems, and of isothermal, adiabatic, isobaric and isothermal changes in state. Connection between work and heat, as illustrated by the steam engine. The molecular interpretation of heat, energy and temperature. The Boltzmann distribution. Meaning of negative temperatures.
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Alert en ondernemend 2.0 : Opleidingsprofiel Culturele en Maatschappelijke Vorming. 4a ed. Uitgeverij SWP, 2014. http://dx.doi.org/10.36254/978-90-8850-020-6.

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Culturele en Maatschappelijke Vorming (CMV) levert als hogere beroepsopleiding aankomende professionals af die mensen gaan ‘ondersteunen bij het vormen van zichzelf en bij het vormgeven aan hun maatschappelijk leven’. Aan wat voor vereisten moeten die professionals voldoen en hoe moeten ze daartoe worden opgeleid? Die vragen krijgen een helder antwoord in Alert en ondernemend 2.0. Dit nieuwe opleidingsprofiel schetst de context en de maatschappelijke opdracht die daaruit voor CMV’ers voortvloeit. Het plaatst CMV in internationale ontwikkelingen (zoals het ontstaan van ‘social work’ en benoemt de ‘body of knowledge’. Hoofdmoot wordt gevormd door de concrete competenties. De wereld is minder overzichtelijk geworden en het beleid weet daar niet altijd goed raad mee. CMV’ers gaan mét de burger op zoek naar houvast. Dit opleidingsprofiel schept duidelijkheid over hun rol en mogelijkheden.
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Clarke, Andrew. Energy and heat. Oxford University Press, 2017. http://dx.doi.org/10.1093/oso/9780199551668.003.0002.

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Energy is the capacity to do work and heat is the spontaneous flow of energy from one body or system to another through the random movement of atoms or molecules. The entropy of a system determines how much of its internal energy is unavailable for work under isothermal conditions, and the Gibbs energy is the energy available for work under isothermal conditions and constant pressure. The Second Law of Thermodynamics states that for any reaction to proceed spontaneously the total entropy (system plus surroundings) must increase, which is why metabolic processes release heat. All organisms are thermodynamically open systems, exchanging both energy and matter with their surroundings. They can decrease their entropy in growth and development by ensuring a greater increase in the entropy of the environment. For an ideal gas in thermal equilibrium the distribution of energy across the component atoms or molecules is described by the Maxwell-Boltzmann equation. This distribution is fixed by the temperature of the system.
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Escudier, Marcel. Compressible pipe flow. Oxford University Press, 2018. http://dx.doi.org/10.1093/oso/9780198719878.003.0013.

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In this chapter gas flow through pipes is analysed, taking account of compressibility and either friction or heat exchange with the fluid. It is shown that in all cases the key parameter is the Mach number. The analyses are based upon the conservation laws for mass, momentum, and energy, together with an equation of state. So that significant results can be achieved, the flowing fluid is treated as a perfect gas, and the flow as one dimensional. Adiabatic pipe flow with wall friction is termed Fanno flow. Frictionless pipe flow with heat transfer is termed Rayleigh flow. It is found that both flows, and also isothermal pipe flow with wall friction, can be limited by choking.
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Kolmičkovs, Antons. Electric Field Effect on Combustion of Pelletized Biomass in Swirling Flow. RTU Press, 2022. http://dx.doi.org/10.7250/9789934227257.

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The Doctoral Thesis examines the control of the swirling flame flow dynamics with an external static electric field by firing the gaseous products of thermal decomposition of pelletized straw, woody biomass, and peat with the aim of more efficient heat production with a decrease of flue gas emissions. The intensification of the downward vortex in the electric field has been determined, ensuring improved mixing of the air vortex with the biomass thermal decomposition gas flow, intensifying the convective mass transfer towards the heating surfaces, and increasing the amount of heat energy produced in the biomass thermochemical conversion process.
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Priedniece, Vivita. Experimental Study and Modelling of Small Capacity Boiler Flue Gas Treatment and Heat Recovery. RTU Press, 2022. http://dx.doi.org/10.7250/9789934227608.

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The Doctoral Thesis includes the development, testing, verification and analysis of household boilers’ flue gas treatment equipment – the fog unit. A model describing the heat and mass transfer, including particulate matter behaviour in the unit, was developed. The model was validated with experimental data at the nominal capacity of the boiler. An insight into the modelling of heat and mass transfer processes inside the unit is given in the Thesis.
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Garber, Elizabeth, e Stephen G. Brush. Maxwell on Heat and Statistical Mechanics: On "Avoiding All Personal Enquiries" of Molecules. Lehigh University Press, 1995.

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Sherwood, Dennis, e Paul Dalby. Ideal gas processes – and two ideal gas case studies too. Oxford University Press, 2018. http://dx.doi.org/10.1093/oso/9780198782957.003.0007.

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This chapter brings together, and builds on, the results from previous chapters to provide a succinct, and comprehensive, summary of all key relationships relating to ideal gases, including the heat and work associated with isothermal, adiabatic, isochoric and isobaric changes, and the properties of an ideal gas’s heat capacities at constant volume and constant pressure. The chapter also has two ‘case studies’ which use the ideal gas equations in broader, and more real, contexts, so showing how the equations can be used to tackle, successfully, more extensive systems. The first ‘case study’ is the Carnot cycle, and so covers all the fundamentals required for the proof of the existence of entropy as a state function; the second ‘case study’ is the ‘thermodynamic pendulum’ – a system in which a piston in an enclosed cylinder oscillates to and fro like a pendulum under gravity, in both the absence, and presence, of friction.
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Capitoli di libri sul tema "HEMT AlN/GaN"

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Khan, Abdul Naim, S. N. Mishra, Meenakshi Chauhan, Kanjalochan Jena e G. Chatterjee. "Influence of Al2O3 Oxide Layer Thickness Variation on PZT Ferroelectric Al0.3Ga0.7N/AlN/GaN E-Mode GR-MOSHEMT". In HEMT Technology and Applications, 39–51. Singapore: Springer Nature Singapore, 2022. http://dx.doi.org/10.1007/978-981-19-2165-0_3.

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Prasad, Santashraya, e A. Islam. "Influence of AlN Spacer Layer on SiN-Passivated AlGaN/GaN HEMT". In Lecture Notes in Electrical Engineering, 233–42. Singapore: Springer Nature Singapore, 2023. http://dx.doi.org/10.1007/978-981-99-0412-9_20.

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Das, Shreyasi, Vandana Kumari, Mridula Gupta e Manoj Saxena. "Gate Leakage Current Assessment of AlGaN/GaN HEMT with AlN Cap Layer". In Computers and Devices for Communication, 459–64. Singapore: Springer Singapore, 2021. http://dx.doi.org/10.1007/978-981-15-8366-7_68.

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Ranjan, Ravi, Nitesh Kashyap e Ashish Raman. "Effect of AlN Spacer Layer on the Proposed MIS-AlGaN/GaN HEMT". In Lecture Notes in Electrical Engineering, 1115–21. Singapore: Springer Singapore, 2020. http://dx.doi.org/10.1007/978-981-15-7031-5_106.

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Alamgir, Imtiaz, e Aminur Rahman. "2D Simulation of Static Interface States in GaN HEMT with AlN/GaN Super-Lattice as Barrier Layer". In Proceedings of International Conference on Soft Computing Techniques and Engineering Application, 457–65. New Delhi: Springer India, 2013. http://dx.doi.org/10.1007/978-81-322-1695-7_53.

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Sufiyan, Nudrat, e Anup Kumar Sharma. "Analytical Modeling and Simulation Study of Thickness of AlN Spacer on Electrical Properties of AlGaN/AlN/GaN HEMT Device". In Lecture Notes in Electrical Engineering, 497–506. Singapore: Springer Nature Singapore, 2024. http://dx.doi.org/10.1007/978-981-99-6855-8_38.

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Lavrijssen, Saskia, e Blanka Vitéz. "Good Governance and the Regulation of the District Heating Market". In Shaping an Inclusive Energy Transition, 185–227. Cham: Springer International Publishing, 2021. http://dx.doi.org/10.1007/978-3-030-74586-8_9.

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AbstractThis chapter discusses how the fundamental values of energy democracy and energy justice and the principles of good governance can play a role in developing a more consistent approach towards the regulation of the energy sector and, more in particular, in dealing with the challenges of regulating the heat transition in the Netherlands in a just way. Energy justice and energy democracy are energy specific concepts that are gaining influence when interpreting and applying the principles of good governance in the energy sector. Both concepts are based on the awareness that the energy transition is a matter for all citizens of the European Union and should not be ignored by policymakers and independent regulators. The heat transition in the Netherlands significantly impacts the position of consumers, prosumers and vulnerable customers, as an ever-larger group of consumers will be disconnected from the gas grid and will be connected to heat networks. Energy democracy and energy justice and the principles of good governance are important values that should guide policy-makers in making choices that affect consumer participation and the protection of vulnerable customers in the heat transition. It is elaborated how energy democracy and energy justice and the principles of good governance indeed can provide a useful framework within which advantages and disadvantages can be weighed of regulatory choices to be made when modernising the regulation of the heat market in a just way. In particular, there remains a lot to gain in terms of flexible regulation and supervision as well as the facilitation of consumer/prosumer participation in the Netherlands. Because it is likely that most heat consumers will remain locked in for a relatively long time in natural monopolies facilitated by older generation heat networks and the lack of alternative heating, substantive consumer-participation could yield positive results regarding community engagement in heat network management and heat supply.
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Peacock, Malcolm, Aikaterini Fragaki e Bogdan J. Matuszewski. "Review of Heat Demand Time Series Generation for Energy System Modelling". In Springer Proceedings in Energy, 53–60. Cham: Springer International Publishing, 2021. http://dx.doi.org/10.1007/978-3-030-63916-7_7.

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AbstractNational heat demand time series are important inputs into national energy system models. Although time series for primary fuel such as gas might be available, heat demand is not and measuring heat demand is only possible for individual buildings. Four different methods are used in this work to generate daily heat demand time series for Great Britain for 2016–2018 from temperature and windspeed and are validated against heat demand derived from national grid gas demand. All seem to model heat demand well.
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Abdelhakim, Meziani, Abdul-Rahman Allouche, Telia Azzedine e Hilmi Unlu. "Tight Binding and Density Functional Theory of Tailoring Electronic Properties in Al1−xInxN/AlN/GaN High Electron Mobility Transistors (HEMTs)". In Topics in Applied Physics, 669–707. Cham: Springer International Publishing, 2022. http://dx.doi.org/10.1007/978-3-030-93460-6_24.

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Raczyński, Maciej, Artur Wyrwa, Marcin Pluta e Wojciech Suwała. "Optimal Energy Portfolios in the Heating Sector and Flexibility Potentials of Combined-Heat-Power Plants and District Heating Systems". In The Future European Energy System, 219–34. Cham: Springer International Publishing, 2021. http://dx.doi.org/10.1007/978-3-030-60914-6_12.

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AbstractThis chapter examines the role of centralized district heating (DH) systems in context of energy system flexibility and decarbonization. The analysis is performed by applying the model TIMES-Heat-EU. Capacity expansion and operation of the district heating generation units is mainly driven by the evolution of the district heating demand, which varies between the REFLEX scenarios. In all scenarios fuel and technology switches toward bioenergy and natural gas leading to CO2 emission reduction. Since the total amount of energy produced (both heat and electricity) is the highest in the High-RES centralized scenario, the corresponding CO2 emissions for district heating are the highest as well. The CO2 emissions can be reduced by ⁓60% in 2050 compared to 2015. Furthermore, the role of thermal energy storage and power-to-heat technologies is examined.
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Atti di convegni sul tema "HEMT AlN/GaN"

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Jiang, Xiangle, Minhan Mi, Can Gong, Yuwei Zhou, Tianhao Liu e Xiaohua Ma. "Simulation on AlN/GaN/AlN/GaN Planar HEMT and Fin-HEMT for Low-Voltage Applications". In 2024 21st China International Forum on Solid State Lighting & 2024 10th International Forum on Wide Bandgap Semiconductors (SSLCHINA: IFWS), 304–6. IEEE, 2024. https://doi.org/10.1109/sslchinaifws64644.2024.10835385.

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Huang, Mingzhi, Kai Liu, Chong Wang e Ziheng Yu. "Study of p-GaN Gate HEMT with ALN Cap Layer". In 2024 21st China International Forum on Solid State Lighting & 2024 10th International Forum on Wide Bandgap Semiconductors (SSLCHINA: IFWS), 210–12. IEEE, 2024. https://doi.org/10.1109/sslchinaifws64644.2024.10835364.

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Bashkatov, Dmitriy D., Timur V. Malin, Vladimir G. Mansurov, Dmitry Yu Protasov, Denis S. Milakhin e Konstantin S. Zhuravlev. "Effect of AlN Interlayer Thickness on 2DEG Parameters in AlGaN/AlN/GaN HEMT Structures". In 2024 IEEE 25th International Conference of Young Professionals in Electron Devices and Materials (EDM), 120–25. IEEE, 2024. http://dx.doi.org/10.1109/edm61683.2024.10615105.

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Namdeo, Eshaan, e Sukwinder Singh. "Substrate-Dependent Characteristics of AlGaN/AlN/GaN DH-HEMT: A Comprehensive Study". In 2024 International Conference on Electrical Electronics and Computing Technologies (ICEECT), 1–6. IEEE, 2024. http://dx.doi.org/10.1109/iceect61758.2024.10739025.

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Haque, Sanaul, Cristina Andrei, Mihaela Wolf, Oliver Hilt e Matthias Rudolph. "Switch Integrated Ka-Band Low Noise Amplifier in GaN/AlN HEMT Technology". In 2024 19th European Microwave Integrated Circuits Conference (EuMIC), 351–54. IEEE, 2024. http://dx.doi.org/10.23919/eumic61603.2024.10732731.

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Hidayat, Wagma, Muhammad Usman, Syeda Wageeha Shakir, Anum ., Iqra Anjum, Shazma Ali e Laraib Mustafa. "Breaking performance barriers: AlN spacer integration boosts GaN HEMTs to higher drive drain current for HEMT-LED". In Fourth iiScience International Conference 2024: Recent Advances in Photonics and Physical Sciences, a cura di M. Yasin A. Raja, Syed A. Haider e Zohra N. Kayani, 2. SPIE, 2024. https://doi.org/10.1117/12.3051934.

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Said, N., D. Saugnon, K. Harrouche, F. Medjdoub, N. Labat, N. Malbert e J.-G. Tartarin. "RF-Robustness enhancement in AlN/GaN HEMT through AlGaN Back-Barrier: nonlinear model analysis". In 2024 19th European Microwave Integrated Circuits Conference (EuMIC), 2–5. IEEE, 2024. http://dx.doi.org/10.23919/eumic61603.2024.10732162.

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Song, Zeyu, Hanghai Du, Zhihong Liu, Han Wang, Weichuan Xing, Jincheng Zhang e Yue Hao. "Strong Polarization AlN/GaN/Si Heterojunction MIS-HEMT for Mm-Wave Low-Voltage Terminal Applications". In 2024 IEEE International Conference on IC Design and Technology (ICICDT), 1–3. IEEE, 2024. http://dx.doi.org/10.1109/icicdt63592.2024.10717668.

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Geng, Xiaomeng, Nick Wieczorek, Mihaela Wolf, Oliver Hilt e Sibylle Dieckerhoff. "Modeling of a Novel GaN-on-AlN/SiC HEMT Including Thermal Effects for Circuit Simulation". In 2024 IEEE Energy Conversion Congress and Exposition (ECCE), 6731–37. IEEE, 2024. https://doi.org/10.1109/ecce55643.2024.10861295.

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Fouzi, Y., E. Morvan, Y. Gobil, F. Morisot, E. Okada, S. Bollaert e N. Defrance. "Nonlinear Modeling of CMOS Compatible SiN/AlN/GaN MIS-HEMT on 200mm Si Operating at mm-Wave Frequencies". In 2024 19th European Microwave Integrated Circuits Conference (EuMIC), 303–6. IEEE, 2024. http://dx.doi.org/10.23919/eumic61603.2024.10732270.

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Rapporti di organizzazioni sul tema "HEMT AlN/GaN"

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Xing, Huili, e Debdeep Jena. Stacked Quantum Wire AlN/GaN HEMTs. Fort Belvoir, VA: Defense Technical Information Center, aprile 2012. http://dx.doi.org/10.21236/ada580523.

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Xing, Huili G., e Debdeep Jena. Ultrascaled AIN/GaN HEMT Technology for mm-wave RT Applications. Fort Belvoir, VA: Defense Technical Information Center, febbraio 2011. http://dx.doi.org/10.21236/ada538446.

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Guérin, Laurence, Patrick Sins, Lida Klaver e Juliette Walma van der Molen. Onderzoeksrapport Samen werken aan Bèta Burgerschap. Saxion, 2021. http://dx.doi.org/10.14261/ff0c6282-93e2-41a7-b60ab9bceb2a4328.

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In het TechYourfuture project ‘Samen werken aan Bèta Burgerschap’, dat plaats vond in de periode maart 2015 - maart 2020, gaven de onderzoekers samen met scholen en bedrijven concreet invulling aan burgerschapsonderwijs. De maatschappij en maatschappelijke vraagstukken worden steeds complexer. Politieke, technologische, economische, sociaal-culturele of ecologische aspecten van een vraagstuk zijn met elkaar verweven. Daarnaast spelen ook globale en lokale dimensies een rol. Er zijn alleen hierdoor al meerdere antwoorden mogelijk op een vraagstuk. Gedurende het project hebben basisschoolleerlingen (wereldwijde) maatschappelijk-technologische vraagstukken geanalyseerd, bediscussieerd en daar oplossingen voor bedacht. Leraren hebben in het project geleerd bèta burgerschap activiteiten te ontwikkelen, uit te voeren en te evalueren. In de kern gaat het er in Bèta Burgerschap om dat leerlingen door groepsgewijs vraagstukken op te lossen burgerschapscompetenties ontwikkelen. Het gaat hier om drie hoofdcompetenties: (1.) Collectieve argumentatievaardigheden, (2.) Attituden ten opzichte van maatschappelijk technologische vraagstukken en, (3.) Bèta- en techniekkennis. In het onderzoek ‘Samen werken aan Bèta Burgerschap’ is gekeken naar de ontwikkeling van deze drie hoofdcompetenties bij leerlingen die deelnamen aan Bèta Burgerschap activiteiten, alsook naar de effecten van de training en video-coaching die de leerkrachten in het project gevolgd hebben. De resultaten hiervan zijn in het onderzoeksrapport te lezen. Het onderzoek laat zien dat Bèta Burgerschap een aanpak is die leerlingen mogelijkheden biedt om te oefenen met groepsgewijs probleem oplossen als burgerschapscompetentie. Door op school met maatschappelijk-technologische vraagstukken aan de slag te gaan, doen leerlingen meer kennis op over deze vraagstukken en worden zij zich meer bewust van wat er in de wereld speelt en van hoe zij zich verhouden tot deze vraagstukken. Om met Bèta Burgerschap aan de slag te gaan en het netwerk denken en de discussie doeltreffend te begeleiden, blijkt het professionaliseringstraject van toegevoegde waarde te zijn.
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Olson, Douglas A. Heat transfer in an aluminum heat exchanger using normal hydrogen gas:. Gaithersburg, MD: National Institute of Standards and Technology, 1994. http://dx.doi.org/10.6028/nist.ir.3987.

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Miller, Jack. Heat networks. Parliamentary Office of Science and Technology, settembre 2020. http://dx.doi.org/10.58248/pn632.

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A heat network provides heating and hot water to an apartment, commercial site or series of buildings close together. It can also provide cooling. There is interest in using them to help reduce greenhouse gas emissions from UK buildings. This POSTnote looks at the technology of heat networks and their sources of heat. It looks at considerations when building new networks. It also outlines a potential future market framework.
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Unknown, Author. L51602 Criteria for Hot Tap Welding Further Studies. Chantilly, Virginia: Pipeline Research Council International, Inc. (PRCI), maggio 1989. http://dx.doi.org/10.55274/r0010102.

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In the gas transmission industry there is a frequent need for modification of existing pipework. Modifications are made primarily by welding on additional pipes and branch connections to existing pipelines. The associated costs of shutting down a pipeline creates a situation whereby it becomes economically feasible to weld onto pipelines containing flowing, pressurized products. The risk of burn through and in particular, the susceptibility to cracking are greatly increased by the rapid cooling rates associated with the high heat sink effect of the flowing gas and in turn can result in excessive hardening of the heat affected zone in ferritic steels. Edison Welding Institute developed new criteria for safe hot tap welding procedures on all ferritic steels. Their approach is based on correlating field measurements of the ability of the pipe to conduct heat (i.e., its heat-sink capacity) to the cooling rate of the weld. Laboratory welding trials with simulated branch and sleeve connections on live pipelines containing natural gas were used to validate the new criteria. The results indicate that structurally sound hot tap repairs can be made with a high level of confidence.
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Madrzykowski, Daniel. Firefighter Equipment Operational Environment: Evaluation of Thermal Conditions. UL Firefighter Safety Research Institute, agosto 2017. http://dx.doi.org/10.54206/102376/igfm4492.

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The goal of this study was to review the available literature to develop a quantitative description of the thermal conditions firefighters and their equipment are exposed to in a structural fire environment. The thermal exposure from the modern fire environment was characterized through the review of fire research studies and fire-ground incidents that provided insight and data to develop a range of quantification. This information was compared with existing standards for firefighting protective equipment to generate a sense of the gap between known information and the need for improved understanding. The comparison of fire conditions with the thermal performance requirements of firefighter protective gear and equipment demonstrates that a fire in a compartment can generate conditions that can fail the equipment that a firefighter wears or uses. The review pointed out the following: 1. The accepted pairing of gas temperature ranges with a corresponding range of heat fluxes does not reflect all compartment fire conditions. There are cases in which the heat flux exceeds the hazard level of the surrounding gas temperature. 2. Thermal conditions can change within seconds. Experimental conditions and incidents were identified in which firefighters would be operating in thermal conditions that were safe for operation based on the temperature and heat flux, but then due to a change in the environment the firefighters would be exposed to conditions that could exceed the protective capabilities of their PPE. 3. Gas velocity is not explicitly considered within the thermal performance requirements. Clothing and equipment tested with a hot air circulating (convection) oven are exposed to gas velocities that measure approximately 1.5 m/s (3 mph). In contrast, the convected hot gas flows within a structure fire could range from 2.3 m/s (5 mph) to 7.0 m/s (15 mph). In cases where the firefighter or equipment would be located in the exhaust portion of a flow path, while operating above the level of the fire, the hot gas velocity could be even higher. This increased hot gas velocity would serve to increase the convective heat transfer rate to the equipment and the firefighter, thereby reducing the safe operating time within the structure. 4. Based on the limited data available, it appears currently available protective clothing enables firefighters to routinely operate in conditions above and beyond the "routine" conditions measured in the fire-ground exposure studies conducted during the 1970s. The fire service and fire standards communities could benefit from an improved understanding of: • real world fire-ground conditions, including temperatures, heat flux, pressure, and chemical exposures; • the impact of convection on the thermal resistance capabilities of firefighting PPE and equipment; and • the benefits of balancing the thermal exposures (thermal performance requirements) across different components of firefighter protective clothing and safety equipment. Because it is unlikely due to trade offs in weight, breathe-ability, usability, cost, etc., that fireproof PPE and equipment will ever be a reality, fire officers and fire chiefs need to consider the capabilities of the protection that their firefighters have when determining fire attack strategies and tactics to ensure that the PPE and equipment is kept within its design operating environment, and that the safety buffer it provides is maintained.
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Locy, Robert D., Hillel Fromm, Joe H. Cherry e Narendra K. Singh. Regulation of Arabidopsis Glutamate Decarboxylase in Response to Heat Stress: Modulation of Enzyme Activity and Gene Expression. United States Department of Agriculture, gennaio 2001. http://dx.doi.org/10.32747/2001.7575288.bard.

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Most plants accumulate the nonprotein amino acid, g-aminobutyric acid (GABA), in response to heat stress. GABA is made from glutamate in a reaction catalyzed by glutamate decarboxylase (GAD), an enzyme that has been shown by the Israeli PI to be a calmodulin (CaM) binding protein whose activity is regulated in vitro by calcium and CaM. In Arabidopsis there are at least 5 GAD genes, two isoforms of GAD, GAD1 and GAD2, are known to be expressed, both of which appear to be calmodulin-binding proteins. The role of GABA accumulation in stress tolerance remains unclear, and thus the objectives of the proposed work are intended to clarify the possible roles of GABA in stress tolerance by studying the factors which regulate the activity of GAD in vivo. Our intent was to demonstrate the factors that mediate the expression of GAD activity by analyzing the promoters of the GAD1 and GAD2 genes, to determine the role of stress induced calcium signaling in the regulation of GAD activity, to investigate the role of phosphorylation of the CaM-binding domain in the regulation of GAD activity, and to investigate whether ABA signaling could be involved in GAD regulation via the following set of original Project Objectives: 1. Construction of chimeric GAD1 and GAD2 promoter/reporter gene fusions and their utilization for determining cell-specific expression of GAD genes in Arabidopsis. 2. Utilizing transgenic plants harboring chimeric GAD1 promoter-luciferase constructs for isolating mutants in genes controlling GAD1 gene activation in response to heat shock. 3. Assess the role of Ca2+/CaM in the regulation of GAD activity in vivo in Arabidopsis. 4. Study the possible phosphorylation of GAD as a means of regulation of GAD activity. 5. Utilize ABA mutants of Arabidopsis to assess the involvement of this phytohormone in GAD activation by stress stimuli. The major conclusions of Objective 1 was that GAD1 was strongly expressed in the elongating region of the root, while GAD2 was mainly expressed along the phloem in both roots and shoots. In addition, GAD activity was found not to be transcriptionally regulated in response to heat stress. Subsequently, The Israeli side obtained a GAD1 knockout mutation, and in light of the objective 1 results it was determined that characterization of this knockout mutation would contribute more to the project than the proposed Objective 2. The major conclusion of Objective 3 is that heat-stress-induced changes in GAD activity can be explained by heat-stress-induced changes in cytosolic calcium levels. No evidence that GAD activity was transcriptionally or translationally regulated or that protein phosphorylation was involved in GAD regulation (objective 4) was obtained. Previously published data by others showing that in wheat roots ABA regulated GABA accumulation proved not to be the case in Arabidopsis (Objective 5). Consequently, we put the remaining effort in the project into the selection of mutants related to temperature adaptation and GABA utilization and attempting to characterize events resulting from GABA accumulation. A set of 3 heat sensitive mutants that appear to have GABA related mutations have been isolated and partially characterized, and a study linking GABA accumulation to growth stimulation and altered nitrate assimilation were conducted. By providing a better understanding of how GAD activity was and was not regulated in vivo, we have ruled out the use of certain genes for genetically engineering thermotolerance, and suggested other areas of endeavor related to the thrust of the project that may be more likely approaches to genetically engineering thermotolerance.
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Ridens, Simons e Brun. PR-316-15606-Z01 Equations of State Comparison for Pipeline Compressor Applications. Chantilly, Virginia: Pipeline Research Council International, Inc. (PRCI), luglio 2016. http://dx.doi.org/10.55274/r0010873.

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In order to have an improved understanding of the applicability of standard EOS in pipeline applications, a set of gas physical property tests were undertaken with sweet and sour natural gas and CO2 mixtures at typical pipeline compositions and conditions, including new high pressure dense phase applications. Specific gas properties tested include gas density (?), specific heat at constant volume (cv), and speed of sound (c or SOS). These results were compared to several of the most commonly used EOS, including NIST, GERG, AGA8, PR, SRK and BWRS, which were also compared to each other.
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DiDomizio, Matthew, e Jonathan Butta. Measurement of Heat Transfer and Fire Damage Patterns on Walls for Fire Model Validation. UL Research Institutes, luglio 2024. http://dx.doi.org/10.54206/102376/hnkr9109.

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Fire models are presently employed by fire investigators to make predictions of fire dynamics within structures. Predictions include the evolution of gas temperatures and velocities, smoke movement, fire growth and spread, and thermal exposures to surrounding objects, such as walls. Heat flux varies spatially over exposed walls based on the complex thermal interactions within the fire environment, and is the driving factor for thermally induced fire damage. A fire model predicts the temperature and heat transfer through walls based on field predictions, such as radiative and convective heat flux, and is also subject to the boundary condition represen-tation, which is at the discretion of model practitioners. At the time of writing, Fire Dynamics Simulator can represent in-depth heat transfer through walls, and transverse heat transfer is in a preliminary development stage. Critically, limited suitable data exists for validation of heat trans-fer through walls exposed to fires. Mass loss and discoloration fire effects are directly related to the heat transfer and thermal decomposition of walls, therefore it is crucial that the representation of transverse heat transfer in walls in fire models be validated to ensure that fire investigators can produce accurate simulations and reconstructions with these tools. The purpose of this study was to conduct a series of experiments to obtain data that addresses three validation spaces: 1) thermal exposure to walls from fires; 2) heat transfer within walls exposed to fires; and 3) fire damage patterns arising on walls exposed to fires. Fire Safety Research Institute, part of UL Research Institutes, in collaboration with the Bureau of Alcohol, Tobacco, Firearms and Explosives Fire Research Laboratory, led this novel research endeavor. Experiments were performed on three types of walls to address the needs in this validation space: 1. Steel sheet (304 stainless steel, 0.793 mm thick, coated in high-emissivity high-temperature paint on both sides). This wall type was used to support the heat flux validation objective. By combining measurements of gas temperatures near the wall with surface temperatures obtained using infrared thermography, estimates of the incident heat flux to the wall were produced. 2. Calcium silicate board (BNZ Marinite I, 12.7 mm thick). This wall type was used to support the heat transfer validation objective. Since calcium silicate board is a noncombustible material with well-characterized thermophysical properties at elevated temperatures, measurements of surface temperature may be used to validate transverse heat transfer in a fire model without the need to account for a decomposition mechanism. 3. Gypsum wallboard (USG Sheetrock Ultralight, 12.7 mm thick, coated in white latex paint on the exposed side). This wall type was used to support the fire damage patterns validation objective. Two types of fire effects were considered: 1) discoloration and charring of the painted paper facing of the gypsum wallboard; and 2) mass loss of the gypsum wallboard (which is related to the calcination of the core material). In addition to temperature and heat flux measurements, high resolution photographs of fire patterns were recorded, and mass loss over the entirety of the wall was measured by cutting the wall into smaller samples and measuring the mass of each individual sample. A total of 63 experiments were conducted, encompassing seven fire sources and three wall types (each combination conducted in triplicate). Fire sources included a natural gas burner, gasoline and heptane pools, wood cribs, and upholstered furniture. A methodology was developed for obtaining estimates of field heat flux to a wall using a large plate heat flux sensor. This included a numerical optimization scheme to account for convection heat transfer. These data characterized the incident heat flux received by calcium silicate board and gypsum wallboard in subsequent experiments. Fire damage patterns on the gypsum wallboard, attributed to discoloration and mass loss fire effects, were measured. It was found that heat flux and mass loss fields were similar for a given fire type, but the relationship between these measurements was not consistent across all fire types. Therefore, it was concluded that cumulative heat flux does not adequately describe the mass loss fire effect. Fire damage patterns attributed to the discoloration fire effect were defined as the line of demarcation separating charred and uncharred regions of the wall. It was found that the average values of cumulative heat flux and mass loss ratio coinciding with the fire damage patterns were 10.41 ± 1.51 MJ m−2 and 14.86 ± 2.08 %, respectively. These damage metrics may have utility in predicting char delineation damage patterns in gypsum wallboard using a fire model, with the mass loss ratio metric being overall the best fit over all exposures considered. The dataset produced in this study has been published to a public repository, and may be accessed from the following URL: <https://doi.org/10.5281/zenodo.10543089>.
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