IMAGING SURFACE ATOMIC-STRUCTURE BY MEANS OF AUGER ELECTRONS

It has recently been demonstrated that the surface atomic structure of single crystals, monolayers, and thin films can be imaged by means of Auger electrons. Angular distribution Auger microscopy (ADAM) produces subatomic resolution images of atomic structure by measuring and displaying the complete angular distribution of low-energy Auger electrons emitted from atoms near the surface of a substrate or thin film. Auger angular distributions contain the silhouettes of surface atoms backlit by emission from atoms located deeper in the solid, revealing the relative positions of atoms near the surface. High-energy Auger electrons have a larger escape depth and are therefore less surface sensitive but contain crystallographic information, particularly the locations of channels in the crystal. Consequently, ADAM is a powerful new technique for the characterization of semiconductor surfaces and epitaxial thin films, and also for fundamental studies of electron physics provided that certain important experimental criteria are met. Described here are recent applications of ADAM to probing the structures of single-crystal surfaces and thin films.