Cation sublattice stacking faults in Cu-rich chalcopyrite CuInSe2

Using transmission electron microscopy, we have found stacking Faults on time cation sublattice in the chalcopyrite structure of CuInSe2. These films are grown by molecular beam epitaxy under Cu-rich conditions, These stacking faults are found to extend large distances in the plane of the film, and are not found to be present in samples not grown in Cu-rich conditions. We suggest that this defect is triggered by a Cu-induced transformation of the surface structure of the growing film.