Deflection detection and feedback actuation using a self-excited piezoelectric Pb(Zr,Ti)O-3 microcantilever for dynamic scanning force microscopy

We have developed a dynamic scanning force microscope (SFM) that utilizes microfabricated Pb(Zr,Ti)O-3, (PZT) cantilever for lever excitation, deflection sensing and tip-sample spacing control. The lever is a unimorph centilever including a sol-gel derived PZT thin film that has high piezoelectric constants in comparison with sputtered ZnO films. For dynamic operation, the excitation ac voltage signal superimposed on the actuation dc voltage is applied to the PZT layer. The variation of vibration amplitude is detected by measuring the change of current through the layer. By actuating the self-excited cantilever to keep the current constant, we obtain topography images without z actuation of the sample-side scanner. The 200-mu m-long PZT microcantilever with the natural resonance frequency of 63.8 kHz has the high actuation sensitivity of 150 nm/V and the maximum range of more than 1.5 mu m. Using the SFM, we have obtained the clear cyclic contact images of an evaporated Au film surface. (C) 1996 American Institute of Physics.