Proceedings Article | 4 April 1997
KEYWORDS: Silicon, Zinc oxide, Ferroelectric materials, Thin films, Oxygen, Aluminum, Crystals, Pulsed laser deposition, Nitrogen, Glasses
High quality ZnO, AlN, PZT thin films were deposited on different substrates (Si, sapphire, Corning glass) by reactive pulsed laser deposition technique using a Nd-YAG laser (lambda equals 1.06 micrometer, tFWHM equals 10 ns, 0.3 J/pulse) as laser source. The depositions were performed in a stainless steel vacuum chamber (base pressure less than 10-6 mbar) as follows: (1) Zn and PZT targets in high purity oxygen atmosphere, (2) Al target in ultrahigh purity nitrogen reactive atmosphere. Low collector temperatures (in the range of 0 - 350 degrees Celsius), high distance target collector (4 - 7 cm), high laser intensities, reactive gas pressure in the range of 10-3 - 10-1 mbar were found to be mandatory requirements for obtaining uniform, appropriate crystalline orientation thin films, with thickness in the range of 2 - 4 micrometer. Typical analysis as: x-ray diffraction, cross section SEM, x-ray photoelectron spectroscopy (XPS), Fourier transmission infrared spectroscopy (FTIR), secondary ion mass spectroscopy (SIMS), optical absorption spectroscopy were used to characterize the deposited films. They evidence the stoichiometric composition, crystalline structure with the c-axis perpendicular to substrate surface, columnar structure, etc. For the piezoelectric properties studies special structures were prepared: substrate (Si, etc.)/Cr(100 angstrom)/Au(1000 angstrom)/ZnO(or AlN, or PZT)/Al in order to configure an electroacoustic transducer for bulk acoustic wave generation and detection. The measurements confirm the good properties of the deposited films.
