Polarized luminescence of defects in CuGaSe2

The linear polarisation of luminescence light allows conclusions on the symmetry of defects in semiconductors with non-cubic symmetry, like chalcopyrites, for which three shallow acceptors have been identified by photoluminescence. The polarisation dependent photoluminescence allows determination of the symmetry of the defects relative to the c-axis of the crystal. A simple geometrical model implies that chalcogen sites show a predominant direction perpendicular to the c-axis, while metal sites show a predominant direction parallel to the c-axis. Since all three shallow acceptors show polarization parallel to the c-axis, it can be concluded that they are situated on a metal site.