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

A fast scanning tunneling microscope (STM) for scanning micron-sized a reas of atomically rough surfaces has been developed. The response tim e 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 fa st electronics and a novel mechanical design to achieve the high bandw idth. The high bandwidth makes the STM capable of nearly real-time pan ning and zooming, allowing for rapid searches over the surface of the sample. The instrument has been used in air to study wear of atomic la yers, and also to perform nanowriting while scanning. In the case of t he wear study, it was found that step edges not only can retreat durin g wear, but can also advance.