Defects-related optical properties of Zn1-xCdxO thin films

We present a systematic investigation on the structural and optical properties of Zn1-xCdxO thin films produced by spray pyrolysis. X-rays diffraction patterns show polycrystalline films grown preferentially along 10021 direction and the incorporation of Cd in wurtzite ZnO without secondary phases up to x = 0.25. Above this concentration, the presence of secondary cubic phases indicates Cd-rich segregation, which is corroborated by optical transmittance/absorbance measurements. At low Cd concentrations, the optical bandgap energy decreases with the increasing of Cd, describing a nearly linear relation with slope 18.4 meV per% of Cd. Photoluminescence measurements show preferential defects emissions around 500 nm, associated with carrier localized and delocalized levels, which can be attributed to the presence of defects due to growth conditions and Cd incorporation. (C) 2016 Elsevier B.V. All rights reserved.