Investigation of chemical bath deposition of CdO thin films using three different complexing agents

Abstract

Chemical bath deposition of CdO thin films using three different complexing agents, namely ammonia, ethanolamine, and methylamine is investigated. CdSO4 is used as Cd precursor, while H2O2 is used as an oxidation agent. As-grown films are mainly cubic CdO2, with some Cd(OH)2 as well as CdO phases being detected. Annealing at 400°C in air for 1h transforms films into cubic CdO. The calculated optical band gap of as-grown films is in the range of 3.37–4.64eV. Annealed films have a band gap of about 2.53eV. Rutherford backscattering spectroscopy of as-grown films reveals cadmium to oxygen ratio of 1.00:1.74±0.01 while much better stoichiometry is obtained after annealing, in accordance with the X-ray diffraction results. A carrier density as high as 1.89×1020cm−3 and a resistivity as low as 1.04×10−2Ω-cm are obtained.