Dynamics of Electron Beam Channeling in Single Atomic Column and in Crystals

Manifestation of channeling effects in quantitative interpretation of atomic-resolution measurements made using scanning transmission electron microscope (STEM) has been observed in imaging and spectroscopic data [1-3]. Here, channeling refers to the path of the electron beam along atomic columns in a crystal. A feature common among STEM probe path in crystals of many different elemental compositions and crystal structures, is oscillation in intensity of the electron beam along one atomic column of a crystal. The oscillations are observed before any significant portion of the intensity is seen to accumulate on neighboring columns, which has been reported in Si [110] and Si [211] [4,5], and shown in Figure 1(a). That oscillations in intensity occur independently of scattering effects from neighboring columns was confirmed by simulating beam behavior in hypothetical individual isolated atomic columns. The physical changes in the STEM probe that lead to oscillation in intensity were expected to be the same in crystals and isolated columns because of the observed similarity in the characteristics of the oscillations, frequency and magnitude. In fact, the level of difference between characteristics of intensity oscillations in crystal and isolated column was systematically outlined based on crystal features, elemental composition and lattice parameters, see Figure 1(b), with an almost exact match shown in Figure 1(c).