Self-excited force-sensing microcantilevers with piezoelectric thin films for dynamic scanning force microscopy

This paper attempts to describe a new type of self-excited force-sensing microcantilever for dynamic scanning force microscopy (SFM). The new microcantilevers have two piezoelectric ZnO layers on an SiO2 film. The upper piezoelectric layer is utilized for exciting the lever and detecting the lever displacement, whereas the lower layer is utilized for controlling the tip-sample spacing. We have fabricated experimental two-layer piezoelectric microcantilevers and characterized them by measuring the frequency dependence of the admittance. In effect, we have successfully constructed a dynamic SFM without the external oscillator and detector with a resolution of less than 0.3 nm at a bandwidth of 125 Hz. The microcantilever can be statically driven by applying d.c. voltages to the lower piezoelectric layer, where the sensitivity of static drive is 4-6 nm V-1.