CONVERGENT-BEAM ELECTRON-DIFFRACTION STUDIES OF EPITAXIAL SI/SIO2 SYSTEMS

Convergent-beam electron diffraction (CBED) techniques have been applied to the study of silicon layers grown laterally on partially oxidized silicon wafers by liquid-phase epitaxy. Energy filtering of the electrons in the microscope provides CBED patterns from cross-sectional and plan-view specimens of large thickness with improved contrast and angular resolution. Cross-sections from the interfacial regions show a splitting or a broadening of the rocking profile of lines in CBED patterns. Strains at the Si-SiO2 interfaces are deduced from the patterns and related to relaxation effects in the special geometry of the cross-sectional specimens. Inference to bulk systems reveals that the Si lattice is in a state of tetragonal distortion close to the Si/SiO2 interface. Large-angle CBED patterns from plan-view specimens reveal a bending of Si layers relative to the substrate. Examples in the study of lateral coalescence of Si layers are demonstrated, such as the reversal of bending of the layers at the sewn where two layers merge or the characterization of strain fields around inclusions in the Si layers.