Anti-phase domain boundaries in ZnGeP2 (ZGP)

Coherently oriented cubic defects were recently reported to exist within the tetragonal lattice of zinc-germanium-phosphide, ZnGeP(2) (ZGP). X-ray diffraction utilizing whole pattern optimization (Rietveld method) and line-profile-fitting (LPF) enabled us to identify these defects. In the present research, transmission electron microscopy (TEM) was used for direct observation of these defects. The bright field and dark field TEM images of the ZGP foil indicate the existence of anti-phase domain boundaries (APB). Electron diffraction patterns clearly reveal two coherently oriented entities, one of a tetragonal symmetry in accordance with the chalcopyrite lattice, the other however of a cubic symmetry. This confirms our former finding of the existence of coherently oriented cubic defects in as-grown chalcopyrite ZGP crystal. (C) 2001 Elsevier Science B.V. All rights reserved.