Effect of fluorine addition on boron doped ZnO transparent electrode by room temperature spray method and thermal treatment

Highlights: ► In this paper we investigate the crystalline, optical and electrical performance of ZnO thin film containing boron and fluorine. ► The boron and fluorine substitution in the ZnO lattice has positive effects in terms of increasing the free electron density and crystallinity of thin film, and these effects consequently improve the optical and electrical properties. ► The obtained B, F–ZnO thin film has great potential as a material for transparent conducting electrode. - Abstract: A room temperature spraying method which reduces the liquid chemical to an aerosol of submicron size droplets was used to deposit B, F–ZnO (precursor: B = 0.02, 0 ≤ F ≤ 0.1) thin films. X-ray diffraction studies demonstrate that B, F–ZnO (precursor: B = 0.02, 0 ≤ F ≤ 0.1) thin films have a wurtzite crystal structure. All XRD peaks have shifted higher angle and the crystal orientation was changed at certain amount of fluorine (>6 at%) in precursor solution. Analysis of X-ray diffraction patterns and X-ray photoelectron spectra revealed that fluorine which was combined with zinc atom (F–Zn) was successfully doped into the ZnO crystal lattice. Analogously to these studies, the scanning electron micrographs show that the grain size tends to decrease. The optimal result of the B, F–ZnO (precursor: B = 0.02, 0 ≤ F ≤ 0.1) films was obtained at B = 0.02, F = 0.06, with a low resistivity level of about 0.17 × 10−3 Ω cm and a high transmittance of 90% in the visible light spectrum (300–800 nm). We propose that the substitution of boron and fluorine in the ZnO lattice has positive effects in terms of increasing the free electron concentration and density of thin film. These results can be improved the optical and electrical properties.