Influence of solution molarity on structure, surface morphology, non-linear optical and electric properties of CdO thin films prepared by spray pyrolysis technique

The polycrystalline Cadmium Oxide (CdO) thin films were grown on glass slides at 693 K by spray pyrolysis technique. A comprehensive study was carried out to understand the influence of precursor concentrations on structure, surface morphology, optical and electrical properties of the deposited films. X-ray diffraction study shown the cubic phase of the deposits preferentially oriented along (2 0 0) plane. The crystallite size gradually increased with increasing solution molaritiy. The structural parameters have shown systematic variation. SEM images showed the change of spheroid shaped crystallites to flower like structure with increasing molarity. The elemental analysis was examined by X-ray photoelectron spectroscopy. The transmittance is reduced and the absorption edge is red shifted with increasing molarity. Photoluminescence spectra display the origin of CdO near band edge emissions (NBE) in addition to green-yellow emission. The third-order nonlinear optical (NLO) properties of CdO films were measured with (CW) DPSS laser at 532 nm. All the samples have exhibited good optical absorptive effects with reverse saturable absorption (RSA) behaviors. The films have shown n-type electrical conductivity that has increased with molarity due to the enhancement of charge carriers in the deposits.