Oriented cadmium oxide thin solid films

Abstract

A chemical bath deposition technique has been developed for the preparation of Cd(O₂)_0.88(OH)_0.24 thin films on glass and quartz substrates from alkaline media at room temperature. These films were then annealed at 473 K in order to obtain cadmium oxide films. Two baths were used for film preparation. X-Ray diffraction analysis clearly showed that the CdO films obtained from a bath without KBr have a preferred crystalline orientation in the 〈200〉 direction while those obtained from a bath containing KBr had only slightly preferred crystalline orientation in the 〈111〉 direction. The optical bandgap, E_g, was evaluated from the VIS absorption spectra. It was found that E_g for the films oriented in the 〈200〉 direction is 2.63 eV, while it is 2.57 eV for those with the slight 〈111〉orientation. The different values of the cross-over terminal points of absorption and transmittance spectra confirm the difference between the films with different crystalline orientation.