Deconvolution of topographic and ferroelectric contrast by noncontact and friction force microscopy

We report on the recent investigations of the surface of ferroelectric crystals with scanning force microscopy. In situ investigations are demonstrated for temperatures T even above the transition temperature T-c for triglycine-sulphate (TGS) and barium-titanate (BaTiO3) (T-c,T-TGS) = 49 degrees C, T-c,T-BaTiO3 = 126 degrees C. We directly observed transition from the ferroelectric into the paraelectric phase. Our inspection of the ferroelectric crystals TGS and BaTiO3 allowed the simultaneous investigation of topographic surface features and ferroelectric domain structure in these crystals. Ferroelectric domains are clearly discernible in the noncontact mode as well as the friction force mode of imaging. The domain wall width in TGS was measured to be smaller than 8 nm. Furthermore, contact force microscopy indicated the domain wall to be atomically flat, exhibiting no surface step. While image contrast in noncontact scanning force microscopy pictures is found to be a convolution of both topographic and ferroelectric forces on TGS samples, the tip/sample interaction in BaTiO3 is dominated by van der Waals forces. (C) 1996 American Vacuum Society.