Growth of CuInSe2 by molecular beam epitaxy

We have used molecular beam epitaxy to grow CuInSe2 layers on CdS (0001B) and other substrates. Epitaxial growth is obtained at a substrate temperature of 300 °C. The ratio of the arrival rates of copper to indium is the key parameter governing layer stoichiometry. In order to produce low-resistivity p-type layers, the Cu/In arrival rate ratio must be slightly higher than that used to grow nominally stoichiometric layers. This suggests that a different defect is controlling electrical properties, rather than the copper vacancy complex which dominates bulk material. We have fabricated CuInSe2/CdS heterojunctions which show a maximum solar conversion efficiency of ∼5%.