A CALIBRATED SCANNING TUNNELING MICROSCOPE EQUIPPED WITH CAPACITIVE SENSORS

Piezoelectric actuators that are used in scanning probe microscopes an d in precision X-Y translation stages have undesirable properties. Pie zoelectric effects like hysteresis, nonlinearity, and drift introduce geometric deformations in the scanning probe microscope images. Due to these deformations, the quantitative interpretation of the absolute s ize of surface features is difficult and often not accurate. A calibra ted X-Y scanning stage has been developed that is combined with a scan ning tunneling microscope. This stage is equipped with capacitive sens ors that measure the X-Y position in real time. By incorporating the s ensors in a feedback loop, it is possible to correct the piezoelectric voltages dynamically and reach the desired scanning positions with a minimal position error. Therefore, a surface can be scanned in a geome trically proper way, and stage drift and low frequency vibrations are corrected in real time. (C) 1996 American Institute of Physics.