Flexure Structural Scanner of Tip Scan Type for High-speed Scanning Tunneling Microscopy

Abstract

Dynamic behaviors of atoms on a material surface are important processes for catalytic reactions and crystal growth. Visualizing their processes will contribute to understanding reaction mechanisms and the process of surface structural formation. Scanning tunneling microscopy (STM) is a powerful tool to investigate the surface structure of solid materials and has been used to observe the atomic structures of various important materials such as metals and semiconductors. However, the scan speed of conventional scanning tunneling microscopes is too slow to capture dynamic processes of surface atoms in real time. In this study, we developed a new scanner for high-speed STM (HS-STM). This scanner is constructed from a flexure structure actuating in the x and y directions and a small piezoactuator actuating an STM tip in the z direction. To enhance the actuation bandwidth, the tip holder was minimized and the flexure was hardened. We successfully imaged atomic structures on both highly oriented pyrolytic graphite under ambient conditions and a Si(111) under ultrahigh vacuum at 1 frame s⁻¹ using the developed HS-STM scanner.