An experimental method, employing a scanning tunneling microscope (STM) as
an actuator and a scanning electron microscope (SEM) as a motion detector,
was developed to study microelectromechanical systems (MEMS) and has been a
pplied to study microfabricated cantilever beams. Vibrations actuated by an
ac voltage applied to the piezodrive are transferred to the sample by the
STM tip, which also provides a constraint at the drive location, altering t
he fundamental mode of the oscillation. A continuous change in the resonant
frequency of the cantilever is achieved by varying the position of the STM
tip. In contrast to the few percent tunability previously demonstrated for
MEMS oscillators, we have varied the cantilever frequency over a 300% rang
e. (C) 2000 American Institute of Physics. [S0003-6951(00)03146-6].