Electrical resistivity and photoluminescence spectrum of layered oxysulfide (LaO)CuS

On growth conditions the dependence of the electrical resistivity and the photoluminescence (PL) spectrum of a layered oxysulfide (LaO)CuS have been investigated. The electrical resistivity shows semiconducting behavior and its magnitude decreases with the increase in the sintering temperature and time, which is considered to introduce structural defects such as Cu or La vacancies. The PL spectrum consists of six emission bands which are assigned to a direct interband transition and the transitions originating in two kinds of donor and acceptor levels corresponding to defect centers in the band gap. The PL spectra depend on the growth conditions. The introduction of lattice imperfection increases the intensity of the wide emission bands, and the (LaO)CuS sample visually appears to be ‘white’ under UV excitation. The white luminescence is an important property for the application to display back-light.