Non-stoichiometry effects on electrical and luminescence properties of the layered oxysulfide (LaO)CuS

The layered oxysulfide (LaO)CuS is a wide-gap semiconductor. In general, the wide-gap semiconductor has strong mono-polarity and non-stoichiometry which affect their physical properties. In this study, the relation between the non-stoichiometry of (LaO)CuS and their physical properties has been investigated. Several kinds of non-stoichiometric samples were prepared. In the Cu non-stoichiometry, (LaO)CuS can accommodate the excess Cu in preference to a deficiency. In the La and S non-stoichiometric samples, deficiencies are preferred. The Cu and S non-stoichiometry affects their electrical and emission properties as expected from the valence band structure. It should be noted that the La nonstoichiometry is also quite effective on the band edge emission and the resistivity as well as other non-stoichiometry. These results reveal that not only Cu but also La deficiency is important in controlling the physical properties. (c) 2005 Elsevier Ltd. All rights reserved.