PYROELECTRIC PROPERTY OF PB5GE3O11 THIN-FILMS PREPARED BY LASER-ABLATION

Pb5Ge3O11 films were prepared by laser ablation, and pyroelectricity was obtained in the films after annealing. Stoichiometric films were formed at oxygen pressures around 5 x 10(-1) Torr during deposition, It was found that an unreported precursor phase was grown on Pt/Ti/SiO2/Si substrates at a temperature of 520 degrees C. Subsequent annealing at 500 degrees C for 2 h in air made it possible for the film to have (001) oriented texture of ferroelectric Pb5Ge3O11. This sample showed remanent polarization of 1.4 mu C/cm(2) with a ferroelectric hysteresis loop of an asymmetric shape and a pyroelectric coefficient of 4.3 nC/cm(2)K, while these values were about one third of those reported for single crystal Pb4Ge3O11 in a polarization direction. The inferiority in this ferroelectricity is thought due to the lead-deficient phase involved in the film. Although this localized second phase still remains, the appreciable reduction in the process temperature for texturing a Pb5Ge3O11 film in the c-plane ns low as around 500 degrees C is attributed to the sufficient supply of oxygen during the deposition.