Project summary and keywords

The purpose of NUOTO is to demonstrate multifunctional properties of new dielectric ceramic, the calcium copper titanate, CaCu3Ti4O12 (CCTO), thin films and proposes to apply them to demonstrate electronic devices for novel industrial applications.

CCTO sintered in powder bulk polycrystals (figure 1), demonstrated to possess an impressive dielectric constant (k) value (105) measured at 1 MHz at room temperature. This radically new property is furthermore coupled with stability from 101 Hz to 106 Hz (it should be increased for Rf applications behind the state of the art up to 3 GHz) and in a wide temperature range (100K – 600K). In principle, this property can allow to fabricate high capacity density planar (2D) condensers. Those devices have an extraordinary and strategic importance in the semiconductor industry. The number of condensers in integrated circuits for wireless communication is going to dramatically increase with the increasing number of capabilities that are included in mobile electronics (phones, computers, ...). Wireless electronics is the faster growing electronics market and has important effects on our quality of life, security, environment and health. Who will be able to provide the best devices will conquer the larger part of the market and a dominant technology in the world.

   O = Red

   Ti = Octahedra

   Ca = Yellow

   Cu = Blue
Figure 1. CCTO unit cell

A first objective will be the development of multifunctional bulk materials with superior performances. Bulk properties will be improved during the project firstly by optimisation of the synthesis of pure CCTO strongly reducing impurities and anomalies. Then, doped CCTO will be investigated to develop new materials with improved performances. At the same time a theoretical approach will be used to build the new materials. They will be investigated regarding to all their properties with particular regard to dielectric, magnetic, ferroelectric or optical behaviour. Finally, CCTO-based phases, composites and related perovskite-based materials with high k as potential ‘next generation’ high k and/or multi-functional materials for electronic applications will be explored.

A second objective will be the thin film deposition obtained by physical methods like laser ablation and sputtering.

A third objective is to develop deposition processes for CCTO by metal organic chemical vapour deposition (MOCVD). As a further breakthrough, new equipment will be developed within the project for laser assisted Chemical Beam Epitaxy (CBE), which uses a laser to change in situ, during the deposition, the CCTO composition. The advantage of this approach is the easily scalability to large surfaces for industrial processes and the possibility to laser irradiate the film during the growth for the properties modification.

A fourth objective will be the full characterisation of all the new material properties (dielectric, but also magnetic, ferroelectric, optics).

A fifth objective will be the fabrication of condensers and antennas (figure 2) to measure dielectric characteristics considering capacitive density, stability in frequency. Other devices will be developed to measure different physical properties.

Figure 2. Example of integrated silicon chip for Rf applications with integrated capacitors. a) planar (2D) b) 3D structures.

Calcium copper titanate, giant dielectric constant, ceramic, electronic devices.

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