Photoluminescence properties of Ge-implanted CuGaSe2 crystals

Photoluminescence (PL) properties of Ge-doped CuGaSe2 single crystals were studied in the temperature range between 8 and 300 K. The doping was done u sing the ion implantation technique. As-grown crystals exhibit two PL bands at 1.68 and 0.96 eV. The Ge doping gives rise to two additional deep PL ba nds at 1.28 and 0.73 eV. Based on the temperature quenching of these PL ban ds we show that the 1.68 and the 0.73 eV PL bands are probably both related to the V-Cu acceptor. We suppose that the (V-Cu-Ge-Cu) complex where the G e donor defect has a double charge is responsible for the 0.73 eV band. The 0.96 and 1.28 eV bands are explained as close donor-acceptor pairs where t he acceptor defect is V-Ga We assume that the single charged Ge-Cu donor de fect paired with the V-Ga is connected with the 1.28 eV PL band while an un known intrinsic donor paired with the V-Ga is responsible for the 0.96 eV b and.