Scanning force microscopy and amplitude versus distance measurements on single-crystal oxide surfaces

摘要

Dynamic mode imaging and investigations on amplitude versus distance measurements were carried out on surfaces of single-crystal; SrTiO3, Al2O3 and LaAlO3. Experiments were performed to optimize the imaging parameters for surfaces having varying elastic properties. The dependence of the amplitude-distance curve on different materials and the amplitude of oscillation was investigated. For SrTiO3, a low-drive amplitude provided the linear region necessary for imaging. A large amplitude of oscillation, however, created dips in the amplitude-distance curves, presumably due to complications in the tip dynamics such as bifurcation, period doubling, etc. In the case of Al2O3 and LaAlO3, amplitude-distance curves were characterized by oscillations for lower tip sample separations and step-like discontinuities in the stiff region. The magnitude of the oscillations and discontinuities was found to decrease with amplitude and eventually could be eliminated. Thus, for these samples a large amplitude of the cantilever provided the linear region required for imaging. It was observed also that two different surf aces of Al2O3 (c-cut and r-cut) yield totally different amplitude-distance curves consistent with their standard differences. The results indicate the complex behaviour of amplitude-distance curves, which not only vary from one sample to another but from one surface to another for a given sample. Copyright (C) 2004 John Wiley Sons, Ltd.