Effect of Target Surface Microstructure on Morphological and Electrical Properties of Pulsed-Laser-Deposited BiFeO_3 Epitaxial Thin Films

摘要

The effect of target surface microstructure on the morphological and electrical properties was studied on pulsed-laser-deposited lead-free ferroelectric BiFeO_3 with a relatively low energy gap of about 2.7 eV and a high absorption coefficient of about 10~5cm~(-1) among ferroelectric materials. It was found that a columnar structure was formed on the target surface during the deposition and that droplet density increased when the columnar structure formed. We modified the driving system for the target to prevent the formation of the columnar structure. With the use of the target driving system, droplet density decreased to 42% relative to that without the use of the system. The effects of the morphology change of the target on the growth and electrical properties of BiFeO_3 epitaxial films were also investigated. With the introduction of the system, breakdown voltage increased from 140 to 290kV/cm and coercive field decreased from 112 to 82kV/cm.