Growth and characterization of CuCdTeO thin films sputtered from CdTe-CuO composite targets

The incorporation of Cu and O in CdTe films grown by rf sputtering using a target comprised of a mixture of CdTe and CuO powders is studied. The Cu and O contents ranged between 5 and 20 at.% and the temperature of the substrate was 250 or 300 °C. Energy dispersive spectroscopy data show the incorporation of Cu and O into the CdTe in a controlled manner. All films resulted polycrystalline with a decreased lattice parameter of the CdTe due to the incorporation of Cu and O. Large Cu and O contents promote the formation of a structural phase of the type Cu2−xTe. The good crystallinity of the CdTe is revealed by the LO mode and its harmonics in the Raman spectra. Bands associated to structural units of [TeO4]4− and [TeO3]2− were identified in Raman and infrared spectra. Films with large Cu and O content present an optical absorption extending from the infrared range to photon energies of the CdTe band gap.