We have developed a method to excite cantilever vibrations for dynamic force microscopy. A n-doped silicon cantilever is coated by platinum. At the interface, a Schottky barrier forms whose depletion layer couples to the elastic strain mainly by Maxwell stress and by electrostriction. If a sinusoidal voltage is applied to the Schottky barrier, the cantilever is excited to periodic vibrations due to the transverse strain generated parallel to the length axis of the cantilever. In atomic force acoustic microscopy contact-resonance spectroscopy, this technique delivers clean resonance spectra devoid of spurious signals.