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# Applications of perovskite oxide thin films: microcantilevers, superconducting devices and dielectric interconnections

Vasta, Giuseppe (2012)
Ph.D. thesis, University of Birmingham.

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## Abstract

The aim of this Phd is to investigate the properties of micro-cantilevers, containing BaTiO$$_3$$ based capacitors on their top and verify if they can be used as energy harvesting devices. SrRuO$$_3$$/BaTiO$$_3$$ systems behaving as high quality (i.e. with an impedance phase between -80° and -90°) capacitive structures, in the frequency range 6KHz - 50KHz and with a residual polarization equal to 2.5 µC/cm$$^2$$ have been fabricated on 400 nm thick MgO sacrificial layer. These structures allow to design micro-cantilevers with a minimum resonance frequency of 6KHz.
Two piezoelectric modes are generally used in energy harvesting devices, they are the 33 and the 31 piezoelectric mode. X-ray diffraction analysis shows that the polar axis of BaTiO$$_3$$ is perpendicular to the surface of the film when this layer is grown on SrRuO$$_3$$ and SrTiO$$_3$$. This configuration fits the 31 energy harvesting mode. When BaTiO$$_3$$ is grown on MgO the polar axis is parallel to the surface of the film so this configuration fits the33 energy harvesting mode.
Micro-cantilevers employing YBa$$_2$$Cu$$_3$$O$$_7$$ and MgO sacrificial layers have been fabricated with a technology developed for the fabrication of Nb/Au/YBa$$_2$$Cu$$_3$$O$$_7$$ ramp type Josephson junctions.

Type of Work: Ph.D. thesis. Tarte, Edward Colleges (2008 onwards) > College of Engineering & Physical Sciences School of Electrical Electronic and Computer Engineering Work related to this thesis is published as Vasta, Giuseppe and Jackson, Timothy J. and Tarte, Edward (2012) Electrical properties of BaTiO3 based ferroelectric capacitors grown on oxide sacrificial layers for micro-cantilevers applications. Thin Solid Films, 520 (7). pp. 3071-3078. http://eprints.bham.ac.uk/1026/ TJ Mechanical engineering and machineryTK Electrical engineering. Electronics Nuclear engineering University of Birmingham Giuseppe Vasta 3217
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