Effect of cobalt chloride concentration on structural, optical and electrical properties of Co3O4 thin films deposited by pneumatic spray

Abstract

Cobalt oxide (Co3O4) thin films at different solution molarities (0.05, 0.1, 0.15, and 0.2mol/l) were successfully
deposited on glass substrates by home-made pneumatic spray pyrolysis system (SPT) where the substrate temperature was
maintained at 400 °C. Different techniques were used to study the properties of the deposited films. These are the X-Ray
diffraction, UV-VIS spectroscopy, energy dispersive spectroscopy (EDS), scanning electron microscopy (SEM) and four
probe points measurements. The obtained Co3O4 thin films are polycrystalline where the crystallites size increases from
19.53 to 26.11 nm when the molar concentration of Co precursor was increasing. SEM images revealed a uniform,
homogeneous and well covered surface without any observable cracks. Peaks associated with Co and O elements are
present in EDS analysis witch confirm the composition of the films. The transmittance spectra in the wavelength range of
300-2000 nm are used to study the optical properties. The optical band gap varied from 1.47 to 2.02 eV in the high energy
region and from 1.41 to 1.45 eV in the low energy region. The electrical conductivity increased from 2.43*10-3 to 8.76*10-2
(Ω
.cm)-1 with the increase of molarity.