Ultrasonic force microscopy in waveguide mode up to 100 MHz

Inagaki, K. and Kolosov, Oleg and Briggs, G. Andrew D. and Muto, S. and Horisaki, Y. and Wright, O. B. (1998) Ultrasonic force microscopy in waveguide mode up to 100 MHz. In: Ultrasonics Symposium, 1998. Proceedings., 1998 IEEE. IEEE, SENDAI, pp. 1255-1259. ISBN 0-7803-4096-5

Abstract

We present experimental results that extend the frequency range of ultrasonic force microscopy (UFM) to 100 MHz, operating in a mode in which the cantilever base is vibrated. In this "waveguide-UFM" mode flexural ultrasonic vibrations are launched down the cantilever as in a waveguide, without exciting any particular cantilever resonance. The nonlinearity of the tip-sample force-distance curve allows the conversion of a modulated ultrasonic frequency into a low frequency vibration of the cantilever, detected using an optical lever at the modulation frequency in an conventional atomic force microscope. Experiments were performed on a sample of InAs self-assembled quantum dots on a GaAs substrate. The dots, of order 10-100 nm in diameter, were clearly resolved up to operating frequencies similar to 100 MHZ, demonstrating the difference in elastic properties. Images were also obtained for a polycrystalline chromium film structure deposited on a silicon substrate.