Scanning nonlinear dielectric microscopy

In this article, scanning nonlinear dielectric microscopy (SNDM) with atomic resolution is reviewed. First, experimental results on the detection of ferroelectric domains are shown following a presentation about the theory and principle of SNDM. Next, a three-dimensional (3D) type of SNDM for measuring the 3D distribution of ferroelectric polarization and noncontact scanning nonlinear dielectric microscopy (NC-SNDM) are proposed. Using NC-SNDM under ultrahigh vacuum conditions, we clearly resolve the electric dipole moment distribution of Si atoms on a Si(111)7 × 7 surface. We also succeeded to resolve a fullerene (C60) molecule. Since the technique is applicable not only to semiconductors but also to both polar and non-polar dielectric materials, SrTiO3 and TiO2 surfaces were observed by NC-SNDM. Finally, we characterize an ultrahigh-density ferroelectric data storage system using SNDM as a pickup device and a congruent lithium tantalate single crystal as a ferroelectric recording medium.