Scanning Tunneling Microscopy

Abstract

Publisher Summary Scanning tunneling microscopy (STM) has been finding ever increasing application in surface physics. STM, even as it is used now, has furnished fascinating results, and undoubtedly, holds the greatest promise for surface physics. This is because of its unique resolution that can approach hundreds of angstroms along the normal to the surface and several angstroms throughout the surface. Tunneling microscopes with a scanned area of tens of microns in size have also been devised as well as those combined with a scanning electron and scanning Auger microscope. This chapter discusses recent works on the scanning tunneling microscopes (STM) studies of surface physical properties. The principles of performance and the known designs of scanning tunneling microscopes (STM) are also described. The potentialities of STM and related problems can be illuminated in more detail by studying two materials—namely, highly oriented pyrolitic graphite (HOPG) and GaAs. The most fascinating results have been obtained from studies of solids with atomic resolution. Among the materials for which atomic resolution has been achieved, HOPG is of substantial importance. It has been an object of numerous STM studies. It is most suitable for fabrication of atomically flat surfaces ∼10 3 A in size by splitting single crystals along the basal plane. Such flat areas permitted observation of atomic resolution images both in high vacuum and in air, and even in distilled water. Graphite inertia to atmosphere makes it a convenient test-object. On the other hand, the investigation of GaAs is of particular interest in view of the wide technological application of this semiconductor and its multilayer structures. As a typical layer width in such structures is from tens to hundreds of angstroms, STM is an appropriate instrument for the studies.