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Contribution à la réalisation de circuits hyperfréquences reconfigurables à partir de couches minces ferroélectriques : des matériaux aux dispositifs

Abstract : This PhD thesis concerns the realization of tunable microwave functions using KTa1-xNbxO3 (KTN) thin films developed at the Unité Sciences Chimiques in Rennes.
Our research work began by developing a thin film characterization method whose measurement conditions were very close to those of our future circuits. The analyses of KTN thin films deposited on different substrates highlighted the strong influence of the chosen substrate on the microwave dielectric properties of KTN.
Thereafter, we realized several sets of demonstrators (interdigital capcitors and stub resonators) with the aim to evaluate the potential of KTN thin films for the realization of microwave agile devices. Numerous substrates and KTN compositions were studied to identify the couple which presents the most interesting performances. KTa0,5Nb0,5O3 thin films deposited on sapphire appeared to be the most promising couple and had been privileged for our future realizations.
Afterwards, new systems of measurement were developed to enable the application of high bias voltages. Several type of circuits were then realized and measured: reflection- and transmission-type capacitors, stop-band and pass-band resonators, phase-shifters and filters. Taken as a whole, measured performances demonstrate the high agility potential of KTN-based circuits. On the other hand, insertion losses are even too elevated. Chemical and electronic research leads to improve the performances of these devices are very promising and let us hope, at mid-term, a possible integration of our agile devices in multistandards front-ends.
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Submitted on : Thursday, March 20, 2008 - 11:44:59 AM
Last modification on : Wednesday, September 16, 2020 - 9:56:33 AM
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Vincent Laur. Contribution à la réalisation de circuits hyperfréquences reconfigurables à partir de couches minces ferroélectriques : des matériaux aux dispositifs. Matière Condensée [cond-mat]. Université de Bretagne occidentale - Brest, 2007. Français. ⟨tel-00265851⟩

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