Observation of nano-size ferroelectric domains and crystals polarity using scanning nonlinear dielectric microscopy

A new type of scanning nonlinear dielectric microscope (SNDM), with an additional function of simultaneous observation of surface morphology, is developed. This is achieved by using an electrically conducting atomic force microscopy cantilever as a probe needle. Using this new SNDM, simultaneous measurements of several ferroelectric materials, such as thin films of PZT on SrTiO₃ substrates, are performed. Topographic and domain images, which are simultaneously taken from the same location of the materials, are successfully obtained. The result shows that nano-sized ferroelectric domain images for PZT thin film having a good correlation with a topographic image were observed. Moreover, we demonstrate that SNDM can measure the crystal polarity of a thin film deposited on a polar substrate without the influence of the substrate polarity.