Investigations on the structural, electrical and optical properties of thin films of CdO(111)

Abstract

Thin films of cadmium oxide (CdO) were prepared by simple nebulized pyrolysis technique by spraying on the amorphous glass substrates at five different volumes (5, 10, 15, 20 and 25 ml) of precursor cadmium acetate dihydrate solution. X-ray diffraction analysis reveals that the prepared films were oriented along with prominent (111) plane having cubic structure in CdO matrix. The surface morphology of these thin films showed sphere like structure was observed from scanning electron microscopic study. Transparency of these samples had decreased from 95 to 80% at longer wavelengths (900–1100 nm) with an increase in precursor solution volume. The energy band gap increases from 2.30 to 2.49 eV belonging to direct transition as the precursor solution volume had increased up to 20 ml and decreased for 25 ml. The presence of the absorption peak around 650 cm−1 corresponding to CdO bond was confirmed by FTIR spectrum. The emission spectrum of CdO thin films were investigated by fluorescence spectrum recorded at room temperature. Hall Effect measurement was carried out to investigate the electrical properties of the as deposited CdO thin films. The resistivity decreased from 36 × 10−2 to 7.54 × 10−3 Ω-cm and the activation energy (Ea) had decreased from 0.20 to 0.096 eV. The hot probe characterization proved, all these thin films were n-type semiconductor.