Current image diffraction (CID) of single crystal metal surfaces

Images of single crystal metal surfaces made with a low energy (<400 eV) scanning electron beam exhibit diffraction patterns in the absorbed current. Dynamical theoretical calculations of the total reflectivity of the surface as a function of incident polar and azimuthal angles at a specified energy indicate that these patterns are primarily due to the elastically backscattered electrons. In this paper, several patterns on aluminum (100), (110), and (111) surfaces and the copper(100) surface are presented, some of which have features quite similar to those of electron channeling patterns that have been observed at much higher energies (several keV). That is, patterns containing dark and light lines corresponding to high and low reflectivities from Bragg planes are observed. The energy dependence of these lines correspond to simple Bragg theory. Thus, the inner potential and layer displacement can immediately be extracted from the images.