Imaging of polytypes and stacking faults in tetrahedral compounds

The resolution attained with a JEOL 200CX electron microscope in top-entry configuration has allowed the direct elucidation of the structure of tetrahedrally bonded compounds. Computer simulation methods were used to calculate through-focus series of images at a range of thicknesses and the conditions for which structural features are interpretable on an atomic scale have been ascertained. In particular, various polytypes are differentiated and stacking faults are intuitively interpreted.