Study of the growth conditions and characterization of CaCu₂O_x and SrCu₂O_x thin films

MCu₂O₂ (M = Ca, Ba, Mg, Sr) are promising materials for the development of new p-type transparent conductive oxide thin films. We report on a study of the growth conditions of MCu₂O_x (M = Ca, Sr) thin films by injection MOCVD and on the characterization of their structural properties. By using calcium or strontium, and copper tetramethylheptanedionate as precursors dissolved in meta-xylene, cuprate films added with either calcium or strontium have been grown by injection MOCVD in the 450 °C-750 °C deposition temperature range. The main factors for the deposition of films presenting good adherence and a high mirror reflection effect are the deposition temperature and the oxygen partial pressure during deposition. As-deposited Ca-based films are mainly composed of CaCu₂O₃ or a mixture of CaCO₃, CaO, CuO and Cu₂O, depending on the oxygen partial pressure and Sr-based films are composed of SrCO₃, CuO. Different annealing under argon atmosphere has been performed in order to obtain the searched phase, which needs the reduction of copper in the 1⁺ oxidation state. We have succeeded to obtain SrCu₂O₂ phase by Rapid Thermal Processing but did not achieve to obtain the Ca-based compound.