The resolution of lattice planes and lattice defects in semiconductors including observations on boundaries

Abstract

A Philips EM300 electron microscope has been employed in conjunction with the tilted illumination 2-beam technique to image the {111} atomic planes in silicon and germanium of 3.14 Å and 3.27 Å spacing, respectively. Slices cut from single crystals and chemically thinned were used. Dislocations of edge-type in a low angle boundary have been imaged in germanium and a correlation observed between diffraction contrast and the lattice strain around a dislocation. The strain around a single edge-type dislocation in germanium is observed to be relatively long range, whereas that around a pair of positive and negative dislocations or adjoining a wall of dislocations is found to be relatively short range extending only a few angstroms. The lattice rotation at a dislocation type boundary is found to be in fair agreement with that calculated from the net edge component deduced by making a Burgers circuit around the wall. Fringes of 2.13 Å measured spacing have been resolved at particles of unknown nature in boron doped silicon, which are taken to be lattice planes. It is suggested that these are the {200} planes (d = 2.17 A ̊ ) of β-SiC.