Abstract
Imaging mechanisms in Piezoresponse Force Microscopy in the high frequency regime above the first contact resonance are analyzed. High frequency imaging enables the effective use of resonance enhancement to amplify weak piezoelectric signals, improves the signal to noise ratio, minimizes the electrostatic contribution to the signal, and improves electrical contact. The limiting factors include inertial stiffening and deteriorating signal transduction, laser spot effects, and the photodetector bandwidth. The analytical expressions for these limits are derived. Furthermore, in the resonance regime, contact stiffness depends strongly on the local elastic properties and topography, resulting in significant variations of the resonant frequency and necessitating efficient frequency tracking methods. High-veracity PFM operation in the 1-8 MHz frequency range is demonstrated and future prospects for high frequency PFM in the 10-100 MHz range are discussed.
