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New materials with Ultra high k dielectric constant fOr TOmorrow wireless electronics

Final Report Summary - NUOTO (New materials with Ultra high k dielectric constant fOr TOmorrow wireless electronics)

Recently, a new ceramic material, calcium copper titanate, CaCu3Ti4O12, (CCTO) has shown a radically new property. It shows an impressive dielectric constant k = 105 at 1 MHz, which is nearly constant over a wide temperature range (100 - 400 K). Therefore, the goal of NUOTO has been to demonstrate multifunctional properties of new dielectric ceramics, mainly the calcium copper titanate, (CCTO), develop the related thin films technology and propose electronic devices for novel industrial applications.

With regard to the development of process fabrication modules for deposition of thin films the project reports that significant improvements have been achieved. Thin film deposition obtained by physical methods like laser ablation and sputtering, demonstrated the possibility to obtain extrinsic properties for dielectric behaviour with a permittivity up to 10(4) at 1 MHz and up to 600 at 1 GHz on several electrodes of industrial interest.

Deposition processes for CCTO by metal organic chemical vapour deposition (MOCVD) have also been improved. The new equipment that has been developed within the project for laser-assisted chemical beam epitaxy (CBE) has proved the possibility of combinatorial deposition, while the processing window for CCTO deposition has been demonstrated as being very narrow, showing the limits of the methods for complex oxide deposition.

The developed methods to characterise the materials permittivity properties at nanoscale have been extensively used to characterise the single crystal, the ceramics and the deposited thin films within the project. In all cases, significant results have been carried out allowing to achieve a nanoscale comprehension of the involved phenomena.

Capacitors were fabricated considering films deposited by the different methods at different partner sites and of different material quality. Specific metal electrodes have been developed and tested. Further electrodes with improved temperature stability have been demonstrated to improve the temperature range of the deposition process. Etching and processing of deposited CCTO thin films have been engineered. A final fabrication process for CCTO capacitors compatible with Si industrial technology has been demonstrated.

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