Properties of ZnO-Cu_2-xSe thin films deposited by sputtering from composite ZnSe-Cu_2O targets

Amorphous and polycrystalline ZnO-Cu2-xSe composite thin films were deposited by rf sputtering using a single target prepared from mixtures of ZnSe and Cu2O powders. Films were grown from three different targets with Cu2O atomic concentrations of 12, 36 and 60% for substrate temperatures between room temperature and 400 °C. The transmittance, reflectance and electrical properties were dependent upon the Cu2O concentration in the target and on the substrate temperature. The optical properties of the polycrystalline films were determined by the copper selenide phases present in the films, which allows foreseeing applications as coatings for windowpanes with strong infrared rejection. The electrical characterization showed that the ZnO-Cu2-xSe composite films are n-type with resistivity values in the range from 3x10−3 to 3x103 Ω⋅cm.