Effects of bath temperature and deposition time on Co3O4 thin films produced by chemical bath deposition

Abstract

Cobalt oxide films have been produced by chemical bath deposition technique at various bath temperatures for different deposition times onto glass substrates. The as-grown Co3O4 films were annealed at 300 degrees C for 1 h and investigated via x-ray diffraction, field emission scanning electron microscopy. The x-ray diffraction patterns have revealed that the annealed samples are polycrystalline with face-centered-cubic structure. The cubic phase is clearly seen in the form of long rods from micrographs. The band gap of the Co3O4 thin films was determined using absorption spectra. The samples have exhibited direct transition with the band gap values lying in the range between E-opt1 = 1.40-1.49 eV and E-opt2 = 2.02-2.19 eV. The refractive index and extinction coefficient as a function of wavelength were investigated from reflectance spectrum by applying the envelope method. The optical parameters of the Co3O4 film, such as dielectric constants, plasma frequency, and carrier concentration, were also evaluated. The electrical properties of the samples constructed planar structure have been measured in the dark at room temperature by applying the voltage values between 1 and 100 V.