Transmission electron microscopy of defects in ZnGeP2

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 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, are 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-gown chalcopyrite ZGP crystal.