AVS 51st International Symposium
    Nanometer-scale Science and Technology Thursday Sessions
       Session NS1-ThA

Paper NS1-ThA2
Nanoelectromechanics of Scanning Probe Microscopies of Ferroelectric Surfaces

Thursday, November 18, 2004, 2:20 pm, Room 213C

Session: Nanoscale Imaging
Presenter: S.V. Kalinin, Oak Ridge National Laboratory
Authors: S.V. Kalinin, Oak Ridge National Laboratory
A. Gruverman, North Carolina State University
J. Shin, Oak Ridge National Laboratory
A.P. Baddorf, Oak Ridge National Laboratory
E. Karapetian, Tufts University
M. Kachanov, Tufts University
Correspondent: Click to Email
Nanoscale applications of ferroelectric materials including MEMS and nonvolatile memory components have motivated a number of studies of ferroelectric behavior on the nanoscale using a wide array of electromechanical Scanning Probe Microscopy techniques including Piezoresponse Force Microscopy, Atomic Force Acoustic Microscopy, Scanning Near-Field Acoustic Microscopy, and Heterodyne Ultrasonic-Electrostatic Force Microscopy. Quantitative interpretation of SPM domain imaging mechanisms and particularly hysteresis loop measurements and tip-induced polarization switching processes requires description of contact mechanics for the ferroelectric surface including electromechanical coupling effects and also the structure of electroelastic fields inside the material. Here, the analytical solution of the coupled electromechanical problem for piezoelectric indentation is used to derive the relationship between indentation force, tip bias and tip displacement. These stiffness relations are utilized for quantitative interpretation of the imaging mechanism of the electromechanical SPM techniques. The structure of the electroelastic fields yields a quantitative measure of the signal generation volume and also provides a quantitative basis for the analysis of tip-induced polarization switching and local hysteresis loop measurements. The early stages of the switching process require the exact structure of the electroelastic fields to be known, while the late stages of switching processes can be adequately described using point charge type models. Tip-induced switching is shown to be possible only above a minimum threshold tip bias, producing a well-defined minimal size of the switched domain. Approaches to reduce minimal written domain size for ferroelectric lithography and data storage are discussed.