A systematic analysis of HREM imaging of elemental semiconductors

The interpretation of high-resolution electron micrographs using the image-matching technique has been examined in a comparative study of <110&-oriented carbon (diamond), silicon and germanium. The usefulness of the calculated intensity distribution at the exit surface of the crystal (exit surface images or ESI) for gaining an understanding of the dependence of image morphology on crystal structure, crystal thickness, accelerating voltage and resolution is emphasized. The effect of the objective lens can, at least partially, be treated in terms of a generalised transfer function for many cases. In this way, characteristic image contrast can be identified and then used to obtain values for relevant parameters required in image matching. Many aspects of the technique are demonstrated experimentally for silicon and germanium at both 100 kV and 400 kV.