A calibrated scanning tunneling microscope equipped with capacitive sensors

Piezoelectric actuators that are used in scanning probe microscopes and in precision X-Y translation stages have undesirable properties. Piezoelectric 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 size of surface features is difficult and often not accurate. A calibrated X-Y scanning stage has been developed that is combined with a scanning tunneling microscope. This stage is equipped with capacitive sensors that measure the X-Y position in real time. By incorporating the sensors 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 geometrically proper way, and stage drift and low frequency vibrations are corrected in real time. (C) 1996 American Institute of Physics.