Single-phase Cu2O and CuO thin films obtained by low-temperature oxidation processes.

The optical and electrical characteristics of copper oxide thin films are greatly dependent on the preparation procedure, which determines the crystallite size and the density of native defects. Minimization of the synthesis temperature is in general desirable to reduce the thermal budget and extend the deposition on sensitive substrates. Here, copper oxide layers have been prepared by heating evaporated copper in air at low temperatures (≤350 °C). The crystalline structure, optical and electrical properties of the oxidized films have been analyzed as a function of the evaporated copper thickness and the heating temperature. Single-phase Cu 2 O and CuO layers have been obtained by adjusting the preparation parameters, which allow to change the visible transmittance and gap energy of the films according to the specific application. Both copper oxide phases exhibit p-type conduction and photosensitivity. The analysis of photoconductivity transients and the optical absorption coefficients made possible to identify the sub-gap defect levels present in these compounds. [ABSTRACT FROM AUTHOR]