HIGH-SPEED SCANNING-TUNNELING-MICROSCOPY - PRINCIPLES AND APPLICATIONS

A fast scanning tunneling microscope (STM) for scanning micron-sized areas of atomically rough surfaces has been developed. The response time of the feedback loop controlling the tip-sample spacing is roughly 5 mu s, and the maximum scan velocity is 1 mm/s. The instrument uses fast electronics and a novel mechanical design to achieve the high bandwidth. The high bandwidth makes the STM capable of nearly real-time panning and zooming, allowing for rapid searches over the surface of the sample. The instrument has been used in air to study wear of atomic layers, and also to perform nanowriting while scanning. In the case of the wear study, it was found that step edges not only can retreat during wear, but can also advance.