Cleavage and Twinning in CuInSe₂ Crystals

Abstract

A study was made of the cleavage and twinning character in single crystals of the chalcopyrite CuInSe2, copper indium diselenide, grown in the laboratory by a vertical Bridgman method. In this material, with a c/a ratio of 2.006, the two main cleavage orientations were found to be {101} and {112} (corresponding to the descriptions {201} and {111}, respectively, in a cubic lattice). The plane identifications were made by measuring angles between adjacent cleaved surfaces and verifying the orientations by X-ray Laue and diffractometry. Cleavage was also found less frequently in a {110} plane, but here microscopic examination of the surface revealed it to consist of ridges in a <110> direction, where the microplanes on either side of the ridge edge were {112} planes. Twinning in the grown crystals was found, by angle measurements and X-ray diffraction, to occur along {112} planes, which is similar to the result in face-centred cubic, diamond and zinc blende lattices, where they are the corresponding {111} planes.

Lattice dynamics and related properties of AIBIII and AIIBIV compounds, I. Elastic constants

“…The elemental composition of crystals grown from stoichiometric melts varies from slightly indium rich at the first-to-freeze end to slightly indium deficient at the last-to-freeze end. The capability of the material to accommodate rather large deviations from stoichiometry and still to crystallise in the chalcopyrite structure finds its explanation in the formation of high concentrations of point defects (vacancies, antisite defects, interstitials) [77,78] and point defect complexes [13], extended structural defects (dislocations, stacking faults, twins) [78,79], orientation domains [80][81][82] separated by small angle grain boundaries [83], and microscopic inclusions of secondary phases in the chalcopyrite matrix [75,81,84]. As an additional complication it must be taken into account that, firstly, there are orientation domains with the CuAu-ordered structure [82] with lattice vibrational characteristics differing from those of the chalcopyrite lattice [85,86] and, secondly, the bond configurations at grain boundaries can considerably differ from the bonding properties in the bulk chalcopyrite matrix [87].…”

Epitaxial growth of CuGaSe 2 thin-films by MBE—Influence of the Cu/Ga ratio

“…The [112] direction is the natural growth direction of chalcopyrites in technologically prepared chalcopyrite films [28]. A stepped (111)A substrate with 5° miscut in [100] direction was used to suppress a growth of independent domains by step flow growth [8].…”

Fracture‐induced reconstruction of a chalcopyrite (CuFeS2) surface

“…For the analogous CuInSe 2 structure, the main cleavage orientations are found to be f101g and f112g and less frequently f110g, although the latter are actually <110> ridges with f112g planes on either side. 38 An early report 39 also indicated cleavage along the (011) plane for CuFeS 2 , equivalent to the f101g set in the tetragonal system. These surfaces are stepped with a residual perpendicular dipole, so should be prone to reconstruction.…”