Scanning tunneling microscopic techniques applied to roughness of silver surfaces

Abstract

The shape of surfaces can be an important factor determining their properties. Likewise, the preparation of surfaces determines their shape. Understanding such processes on the microscopic level requires a variety of sophisticated probes, each with their limitations and advantages. The scanning tunneling microscope (STM), although a newcomer in this area, has the power to investigate surface properties with very high resolution. In this paper I discuss the application of STM techniques to the roughness of silver surfaces, where the roughness of the surface is generated by a variety of preparation methods, by adsorption on the surface, and by creation of structures with the STM itself. Examples are also given of local probes that provide spectroscopic information. Limitations and problems associated with the investigation of rough surfaces are covered, as well as an outlook to the applicability of STM to other areas such as adhesion, friction and engineering given. Finally I shall discuss some of the first results on the emission of photons from the tip-surface region of the STM. In the tunnel mode a large photon intensity is found in the optical range for silver films. These studies demonstrate an interesting link between STM and optical science. © 1989, SPIE.