Influence Of Ph, Doping And Annealing On Structural And Optical Properties Of Chemical Bath Deposited Cobalt (Iii) Oxide (Co3o4) Thin Films

ABSTRACT

Cobalt (III) oxide (Co3O4) thin films were deposited on glass substrates at a temperature of

70°C with continuous stirring and heating of the alkaline bath of various pH of 8, 10, 12 and

14. Cobalt (II) chloride hexahydrate (CoCl2·6H2O) was used as source of Co2+ and to make it

alkaline, 25% aqueous ammonia solution was added as the complexing agent with constant

heating and stirring. The bath was doped with zinc nitrate (Zn(NO3)2 and later, some samples

were annealed at 200°C for 30 minutes. X-ray diffraction method was used to confirm the

depositions. The structural features obtained from the x-ray diffraction showed the peaks of

Co3O4 and increase in crystallinity as pH increases which was confirmed by SEM. It also

shown improvement in crystallinity after doping and annealing. The optical studies showed a

variation of absorbance, reflectance, direct band gap energy and refractive index as pH varies

and changes after doping and annealing. The range of direct band gap energy and refractive

index obtained are 1.34eV - 2.85eV and 1.38 - 2.07 respectively. The values of the band gap

energy and refractive index obtained indicate possible applications in photovoltaic systems,

optoelectronics, laser diodes and light emitting diodes.

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