| 1. |
- Edwards, M.J., et al.
(författare)
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Pressure and temperature dependence of GaN/AlGaN high electron mobility transistor based sensors on a sapphire membrane
- 2012
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Ingår i: Physica Status Solidi (C) Current Topics in Solid State Physics. - : Wiley. - 1862-6351. ; 9, s. 960-963
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Tidskriftsartikel (refereegranskat)abstract
- This paper reports a high pressure sensor based on a GaN/AlGaN High Electron Mobility Transistor (HEMT) that uses its 375 mm thick sapphire substrate to provide a robust base and enables device operation up to at least 60 bar (6 MPa). Transduction of changes in ambient pressure occurs via piezoelectric and pyroelectric effects on the channel conductance. The HEMTs were strategically placed along an 8 mm 2 GaN/AlGaN/GaN/sapphire chip; where the central 4 mm diameter behaves as a pressure sensitive 'drumskin'. The location of peak response lies in the HEMT at the geometric centre of the drumskin, demonstrated by the change in I DS when the pressure was increased from 0 to 60 bar. The response of six strategically placed HEMTs along the chip's surface, were compared to a finite element model to predict sensor behaviour. © 2012 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.
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| 2. |
- Edwards, Michael, et al.
(författare)
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Modelling and optimisation of a sapphire/GaN-based diaphragm structure for pressure sensing in harsh environments
- 2010
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Ingår i: Conference Proceedings - The 8th International Conference on Advanced Semiconductor Devices and Microsystems, ASDAM 2010. - 9781424485758 ; , s. 127-130
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Konferensbidrag (refereegranskat)abstract
- GaN is a potential sensor material for harsh environments due to its piezoelectric and mechanical properties. In this paper an 8mm diameter sensor structure is proposed based on a GaN / AlGaN / sapphire HEMT wafer. The discs will be glass-bonded to an alumina package, creating a 'drumskin' type sensor that is sensitive to pressure changes. The electromechanical behaviour of the sensor is studied in an attempt to optimise the design of a pressure sensor (HEMT position and sapphire thickness) for operation in the range of 10 - 50 bar (5 MPa) and above 300°C. ©2010 IEEE.
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| 3. |
- Pauli, H., et al.
(författare)
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Recent Plant Diversity Changes on Europe's Mountain Summits
- 2012
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Ingår i: Science. - : American Association for the Advancement of Science (AAAS). - 0036-8075 .- 1095-9203. ; 336:6079, s. 353-355
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Tidskriftsartikel (refereegranskat)abstract
- In mountainous regions, climate warming is expected to shift species' ranges to higher altitudes. Evidence for such shifts is still mostly from revisitations of historical sites. We present recent (2001 to 2008) changes in vascular plant species richness observed in a standardized monitoring network across Europe's major mountain ranges. Species have moved upslope on average. However, these shifts had opposite effects on the summit floras' species richness in boreal-temperate mountain regions (+3.9 species on average) and Mediterranean mountain regions (-1.4 species), probably because recent climatic trends have decreased the availability of water in the European south. Because Mediterranean mountains are particularly rich in endemic species, a continuation of these trends might shrink the European mountain flora, despite an average increase in summit species richness across the region.
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