Imaging of ferroelectric domains by atomic force aoustic microscopy

Atomic Force Microscopy (AFM) is a near-field technique to generate high-resolution images of surfaces. A microfabricated elastic beam with an integrated sharp sensor tip at its end is scanned over the sample surface. With a variety of dynamic modes, leading to microscopies such as Force Modulation Microscopy, Ultrasonic Force Microscopy, Atomic Force Acoustic Microscopy, Microdeformation Microscopy, Scanning Local Acceleration Microscopy or Pulsed Force Microscopy, images can be obtained in which the contrast depends on the elasticity of the sample surface. In our Atomic Force Acoustic Microscopy (AFAM) setup, we evaluate the cantilever vibration spectra at ultrasonic frequencies in order to discern local elastic data quantitatively. Either the sample is insonified or the cantilever suspension is excited at ultrasonic frequencies. The vibration spectra of the cantilever depend on the local sample stiffness and hence on the local elasticity of the constituents of the sample. Acoustical images can be obtained by measurement of the cantilever vibration amplitude at a fixed frequency close to a contact resonance with the help of a lock-in amplifier. In this contribution we present AFAM results for contact spectroscopy and imaging of the domain structure of ferroelectric ceramics.