排序方式: 共有8条查询结果,搜索用时 31 毫秒
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Das J. Oprins H. Ji H. Sarua A. Ruythooren W. Derluyn J. Kuball M. Germain M. Borghs G. 《Electron Devices, IEEE Transactions on》2006,53(11):2696-2702
AlGaN/GaN high electron mobility transistors (HEMT) on sapphire substrates have been studied for their potential application in RF power applications; however, the low thermal conductivity of the sapphire substrate is a major drawback. Aiming at RF system-in-a-package, the authors propose a flip-chip-integration approach, where the generated heat is dissipated to an AlN carrier substrate. Different flip-chip-bump designs are compared, using thermal simulations, electrical measurements, micro-Raman spectroscopy, and infrared thermography. The authors show that a novel bump design, where bumps are placed directly onto both source and drain ohmic contacts, improves the thermal performance of the HEMT 相似文献
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Hannelore Derluyn Dominique Derome Jan Carmeliet Eric Stora Rémi Barbarulo 《Cement and Concrete Research》2012,42(10):1379-1388
Durability of reinforced concrete is crucial for civil and building infrastructures. Deterioration related to corrosion of the reinforcement can be caused by chloride diffusion or carbonation due to atmospheric CO2 ingress. Chlorides and CO2 transport coefficients are dependent on the saturation degree of the porous material. Thus, the durability of concrete elements submitted to cyclic atmospheric conditions could depend on the hysteretic moisture behavior of concrete. To assess this influence, an analytical model has been developed describing hysteretic moisture behavior based on the independent domain theory. This model is incorporated in a finite element code for coupled heat and mass transfer, allowing to calculate the concrete response to changing temperature and relative humidity conditions. A comparison is made between simulations using the hysteresis model and using either the main ad- or desorption curve. The results show that durability risks may be underestimated when omitting moisture hysteresis in the outer concrete layer. 相似文献
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Morelle Christophe Théron Didier Derluyn Joff Degroote Stefan Germain Marianne Zhang Victor Buchaillot Lionel Grimbert Bertrand Tilmant Pascal Vaurette François Roch-Jeune Isabelle Brandli Virginie Avramovic Vanessa Okada Etienne Faucher Marc 《Microsystem Technologies》2018,24(1):371-377
Microsystem Technologies - Starting from Gallium Nitride epitaxially grown on silicon, pre-stressed micro-resonators with integrated piezoelectric transducers have been designed, fabricated, and... 相似文献
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Hannelore Derluyn Hans Janssen Jan Carmeliet 《Construction and Building Materials》2011,25(9):3685-3693
This paper presents an experimental and quantitative analysis of capillary transport across the interface brick–mortar joint in masonry. Moisture profiles are measured with X-ray projection. The influence of curing conditions is analyzed by considering three types of mortars: cured in a mould, between capillary wet and dry bricks. A decrease in moisture inflow for the mortars cured between bricks is measured. The pore structure and the moisture transport properties of mortar change significantly due to water extraction from the initially wet mortar to the bricks during curing. Numerical simulations reveal the existence of a hydraulic interface resistance between brick and wet/dry cured mortar. 相似文献
5.
Medjdoub F. Derluyn J. Cheng K. Leys M. Degroote S. Marcon D. Visalli D. Van Hove M. Germain M. Borghs G. 《Electron Device Letters, IEEE》2010,31(2):111-113
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This article presents an experimental and analytical study of the hygric behaviour of mortar joints, with specific attention to the influences of the curing conditions. Capillary water uptake in masonry is visualised with the X-ray projection method and approximated with the sharp-front-theory. The results imply that the curing of the mortar between bricks modifies its hygric properties and introduces an interface resistance, with the effects proportional to the water extraction from the mortar during the curing.The presented study uses the analytical sharp-front theory to analyse the X-ray-visualised moisture content profiles. Validation of the sharp-front findings with independently determined hygric properties and interface resistances confirms the reliability of the approach. The method's main advantage is its ease of application for interpretation of experiments, as the X-ray visualisations suffice as sole input data. The easy applicability is finally demonstrated on an independent measurement, which again corroborates the earlier findings. 相似文献
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Kai Cheng M. Leys S. Degroote B. Van Daele S. Boeykens J. Derluyn M. Germain G. Van Tendeloo J. Engelen G. Borghs 《Journal of Electronic Materials》2006,35(4):592-598
In this work, we report on the growth by metalorganic vapor phase epitaxy (MOVPE) of GaN layers on AlN/Si(111) templates with
step-graded AlGaN intermediate layers. First, we will discuss the optimization of the AlN/Si(111) templates and then we will
discuss the incorporation of step-graded AlGaN intermediate layers. It is found that the growth stress in GaN on high-temperature
(HT) AlN/Si(111) templates is compressive, although, due to relaxation, the stress we have measured is much lower than the
theoretical value. In order to prevent the stress relaxation, step-graded AlGaN layers are introduced and a crack-free GaN
epitaxial layer of thickness >1 μm is demonstrated. Under optimized growth conditions, the total layer stack, exceeding 2
μm in total, is kept under compressive stress, and the radius of the convex wafer bowing is as large as 119 m. The crystalline
quality of the GaN layers is examined by high-resolution x-ray diffraction (HR-XRD), and the full-width-at-half maximums (FWHMs)
of the x-ray rocking curve (0002) ω-scan and (−1015) ω-scan are 790 arc sec and 730 arc sec, respectively. It is found by
cross-sectional transmission electron microscopy (TEM) that the step-graded AlGaN layers terminate or bend the dislocations
at the interfaces. 相似文献
8.
Scaling effects in AlGaN/GaN HEMTs: Comparison between Monte Carlo simulations and experimental data
S. Russo A. Di Carlo W. Ruythooren J. Derluyn M. Germain 《Journal of Computational Electronics》2006,5(2-3):109-113
AlGaN/GaN based HEMTs are showing an unexpected behaviour of the transport characteristic compared to the GaAs and InGaAs
HEMT technology. A downscaling of the source-gate and gate-drain lengths of GaN HEMTs produced a maximum output current increase,
which is not compatible with a framework where the electrons velocity is saturated. Monte Carlo simulations are able to reproduce
this experimental behaviour showing how this phenomena is related to intrinsic velocity-field relation in GaN. We attribute
the lack of overshooting phenomena to the high scattering rate of III–V nitrides and to the strong localisation of the high
electric field region. We also have found that such suppression could be avoided with a proper scaling of the devices. 相似文献
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