Ferroelectrics, microsystems and nanotechnology

Abstract

Ferroelectric materials possess many useful properties which are widely exploited in electronic devices, from the pyroelectric infra-red detectors used in remote light switches and door openers through piezoelectric ceramics and single crystals used for sound generators and frequency stabilization/filtering SAW devices in mobile phones to high value chip-capacitors. These properties also make them useful materials for microsystem devices and in nanotechnology. In recent years, the ability to grow thin and more recently thick, films of ferroelectric oxides at relatively low temperatures has greatly increased their potential for use in novel micro-engineered devices. Examples are: low cost thermal imaging arrays using thin pyroelectric films deposited directly upon silicon chips for applications such as automotive and people sensing/monitoring devices; piezoelectric ultrasonic micro-motors and thin film bulk acoustic resonators for frequency control and filtering in mobile communications. In the field of nanotechnology, the SPM can now be used to manipulate domains in ferroelectric thin films on the scale of 200nm or less, bringing new possibilities in the field of high density information storage and other novel reconfigurable devices at the nanometre scale. The commercial exploitation of many of these devices and effects will depend upon the ability to grow good quality ferroelectric thin and thick films onto a range of substrates at low temperatures (ca. 500°C). (5 pages)