Studies on structural, optical and electrical properties of boron doped zinc oxide films prepared by spray pyrolysis technique

Abstract

Boron doped and undoped zinc oxide (ZnO) thin films were prepared by pyrolytic decomposition of methanolic solution of zinc acetate onto glass substrates. The structural properties of the films were studied by using X-ray diffraction. The results show that both the boron doped and undoped films exhibit hexagonal wurtzite structure with strong c-axis orientation as evidenced by X-ray diffraction patterns. The crystallite size wanes with increasing doping concentration. The electrical resistivity studies were carried out using the four-probe method. It is found that the films with 0.8 wt% boron doping concentration attains the lowest resistivity (10 −4 Ω m), whereas for higher and lower doping concentrations resistivity increases. The thermoelectric power studies showed that the doped and undoped films exhibit n-type conductivity, optical studies revealed that with increase in doping concentration the transmittance of the film increases in the wavelength range 400–600 nm. The optical absorption data were used to determine band gap energy and it is found to be 3.22 eV for undoped ZnO films and 3.32 for boron doped films.