Direct Imaging of Epitaxial Layers by Auger Electrons

Abstract

It has recently been demonstrated that the surface atomic structure of materials 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 Auger electrons emitted from atoms near the surface of a solid material or thin film. Auger angular distributions contain the “silhouettes” of surface atoms “backlit” by emission from atoms located deeper in the solid. The locations and shapes of these silhouettes directly reveal the relative positions of atoms near the surface.Consequently, ADAM is an exciting new technique for characterizing materials surfaces and epitaxially grown surfaces.Auger electrons have been employed for surface elemental analysis and depth- profiling for many years. The limited escape-depth of Auger electrons makes Auger spectroscopy inherently sensitive to the surface region. Depth profiling of materials, often performed in combination with ion etching, is widely used. ADAM offers the possibility of nondestructively obtaining profiles and structural information concerning buried interfaces and can also yield images of atomic structure.