Electrical and optical characterization of oxygen doped CuInSe2 crystals

From a combined study of the electrical properties between room temperature and 77 K and optical absorption at 300 K of bulk CuInSe2 samples doped wit h different oxygen concentrations, two shallow acceptor levels are found. T he activation energy E-A1 and E-A2 of these levels in the dilute limit tend s to be around 30 and 36 meV, respectively. The increase of E-A1 and decrea se of E-A2 with the increase of oxygen content can be explained consistentl y on the basis that the ratio of Cu to In atoms increases with the increase of oxygen incorporated into CuInSe2 lattice.