CONFOCAL SCANNING OPTICAL MICROSCOPY OF BAXSR1-XTIO3 THIN-FILMS

An optical technique based on confocal scanning optical microscopy (CS OM) is used to image the ferroelectric polarization of BaxSr1-xTiO3 (B ST) thin films at room temperature with submicron spatial resolution. BST films were grown by pulsed laser deposition on (100) SrTiO3 and Mg O substrates at 750 degrees C in 300 mTorr of oxygen and postdepositio n annealed in flowing oxygen at temperatures less than or equal to 125 0 degrees C. Films of both paraelectric (x=0.5) and ferroelectric (x=0 .8) compositions show a coexistence of both paraelectric and ferroelec tric phases. The ferroelectric regions exhibit polarization switching and hysteresis at relatively low (1-2 kV/cm) applied fields. These res ults suggest that nonuniform stress is responsible for the strong inho mogeneous thermal broadening of the ferroelectric phase transition, an d that dielectric loss in thin films may be dominated by a relatively small fraction of nanometer-sized regions. (C) 1997 American Institute of Physics.