Effect of fluorine and boron co-doping on ZnO thin films: structural, luminescence properties and Hall effect measurements

In this work, undoped and fluorine and boron co-doped ZnO (ZnO:B:F) thin films have been prepared at 400 °C by using Ultrasonic Spray Pyrolysis technique and optical, electrical, structural, surface and luminescence properties of the films have been investigated. Transmission spectra have been taken by UV–VIS spectrophotometer. It is found that ZnO:B:F films have high average optical transmittance. X-ray diffraction (XRD) patterns indicate that the obtained ZnO:B:F has a hexagonal wurtzite type structure with (002) preferential orientation. The crystallite size is calculated by Debye–Scherrer and Williamson–Hall method. Photoluminescence (PL) spectra of the films have been used at room temperature in order to obtain optical properties of the films. Green emission and UV emission band are observed in PL spectra of ZnO and ZnO:B:F. Surface morphologies of the films have been examined using Scanning Electron Microscope (SEM). Compositional analysis has been performed by EDX. The electrical resistivity, carrier concentration and Hall mobility have been measured. The highest Hall mobility of 13.22 cm² v⁻¹s and the lowest electrical resistivity of 3.13 × 10⁻⁴ Ω cm were obtained at the optimal boron-fluorine co-doping concentration of 5 at.%. All of the results have been appreciated in point of view of optoelectronic industry and photovoltaic solar cell applications and it has been concluded that B–F co-doping has a positively effect on electrical properties.