ANNEALING EFFECT ON STRUCTURAL AND OPTICAL PROPERTIES OF COPPER-DOPED BISMUTH TRIOXIDE Cu:Bi2O3 THIN FILMS

Abstract

In this work, we have examined the effect of annealing temperature on Cu-doped Bi2O3 thin films at 1%, 3% and 5% doping rate successfully prepared by spray pyrolysis technique onto glass substrates. The obtained films were subsequently annealed at different temperature for 4[Formula: see text]h. GIXRD analysis reveals the polycrystalline nature of deposited films and shows the formation of mixed [Formula: see text]- and [Formula: see text]-Bi2O3 phases. With the increase of doping rate, [Formula: see text]-phase of Bi2O3 was identified at medium temperature. The average grain size of thin films at different doping rate of Cu decreases with the increase of annealing temperature. The optical characterization shows that the optical transmittance of the films decreases with the increase of annealing temperature in the range (70–50%) and (40–10%) for 1% and 5% doping rate of Cu, respectively. The evaluation of the optical bandgap energy reveals that the indirect transition is controlling the optical response of the films. The optimum annealing temperature to reduce Bi2O3 energy bandgap to be 3.09[Formula: see text]eV, is 450∘C and 550∘C for 3% and 5% doping rate of Cu.