CHARACTERISTICS OF PZT THIN-FILMS AS ULTRA-HIGH DENSITY RECORDING MEDIA

Ferroelectric thin films as the recording media of scanning probe micr oscope based storage devices were investigated using an atomic force m icroscope(AFM) technique. Polarization domains were formed in the PbZr xTi1-xO3(PZT) thin films epitaxialy grown on the epitaxial SrRuO3(SRO) thin films on SrTiO3 substrate by applying a pulse voltage between th e conductive tip of AFM and SRO as a bottom electrode. The polarized d omains were observed by detecting the inverse-piezoelectricity-induced surface vibration of the PZT thin film caused by applying an ac modul ation voltage to the conductive tip. The recording density of polarize d domains, domain switching speed and preliminary retention characteri stics of polarized domains were studied. The polarized domains as smal l as 30 nn are formed in the PZT thin film with the thickness of 45 nm . The small domains can be formed by applying a 100 us pulse of 10 V t o the conductive tip. As for the retention characteristics of polarize d domains with a size of 90-110 nm, the temperature dependence of doma in retention time was found to be in accordance with the Arrhenius mod el. Extrapolation of the Arrhenius plot leads to an estimation that th e time for 50% of polarized domains to become smaller than half initia l size at 50 degrees C is 34 years for 90-110 nm polarized domains in the 45 nm PZT thin film.