A TEM STUDY OF THE CRYSTALLOGRAPHY AND DEFECT STRUCTURES OF SINGLE-CRYSTAL AND POLYCRYSTALLINE COPPER INDIUM DISELENIDE

A TEM study of the crystallography and defect structure of the ternary compound semiconductor CuInSe2 has been carried out. Single crystal samples grown by the vertical Bridgman technique and polycrystalline films grown by a magnetron sputtering technique were studied. A convergent beam diffraction ZAPMAP for CuInSe2 was assembled and indexed which allowed us to perform systematic defect analysis experiments. Selected area diffraction patterns from a number of zone axes have been compared with theoretically calculated patterns and some subtle differences which have been noted have been explained in terms of double diffraction and/or inelastic scattering effects. We have also demonstrated a qualitative method of studying anti-site defect densities in these crystals by studying diffuse diffraction effects and the intensities of weak Bragg reflections in selected area diffraction patterns. Polycrystalline films tend to exhibit planar defects such as microtwins and stacking faults on (112) planes and the origin of these faults has been explained in terms of growth accidents occurring on low energy facet planes. The single crystal samples do not have planar defects, but tend to contain dislocations. Some of these dislocations have been identified to be <110>-type superdislocations, which consist of two a/2<110> dislocations on the same slip plane, coupled with an antiphase boundary.