Domain structure of (100) strontium bismuth tantalate (SBT) SrBi2Ta2O2 films

(100) Strontium bismuth tantalate (SBT) SrBi2Ta2O9 films(similar to 114-234 nm thickness) on (111) Pt deposited by chemical solution deposition (CSD) and chemical vapor deposition (CVD) were investigated with tapping mode sca nning force microscopy (TMSFM). The domain structure was found to be strong ly influenced by film composition and defect density. Ideal samples showed an a-axis-oriented material with in-plane 180 degrees domains of similar to 22 nm width (film thickness 180-225 nm). The domains were visible by a sur face corrugation of 0.5-2 nm downwards at the site of domain walls, which f ollowed [001] planes. In samples with slightly higher defect density in-pla ne 180 degrees domains, normal-to-plane 180 degrees domains (similar to 10 nm difference in corrugation between differently poled domains) and 90 degr ees domains (similar to 5 nm difference in corrugation between differently poled domains) occurred. Finally, for (100) SET samples, which deviated fro m the ideal composition by several percent, this very high defect density p recluded the ordered formation of domain walls. Instead, as-grown a(1) and a(2)-axis oriented SET films showed random orientation of whole crystallite s poled either in or normal to the surface. The observed surface corrugatio n between two differently poled crystallites was > 10 nm. Single crystallit es as well as single domains could be activated and their polarization stat e was switched mechanically with an electron beam deposited (EBD) or a plas ma-sharpened silicon supertip (SSS) by a force of similar to 5 nN. (C) 2001 Elsevier Science B.V. All rights reserved.