Scanning Probe Microscopy Characterization of Ferroelectrics Domains and Domains Walls in KTiOPO4

Abstract

We use the inverse piezoelectric effect to image artificially made ferroelectric domains of periodically poled KTiOPO4 crystals and KTiOPO4 waveguides using scanning probe microscopy. On applying a high-frequency AC electric field between a gold-coated scanning probe microscope tip in contact with the crystal surface and an electrode below the ferroelectric crystal, the crystal surface oscillates at the frequency of the applied electric field due to the inverse piezoelectric effect. With this technique, and by monitoring the vertical deflection of an AFM tip, which gives contrast between the domains, while the lateral deflection of the tip gives contrast at the domain walls, we determine the apparent domain wall width of the ferroelectric domains to be approximately 20–80 nm for the KTiOPO4. The lateral resolution of this imaging technique is estimated to be about 1 nm.