Effect of Boron-doping and annealing on the structure, morphological and optical properties of ZnO films prepared by spray pyrolysis method

Abstract

Abstract Investigations have been conducted into the structure, morphology, thickness, and optical properties of ZnO thin film upon doping it with Boron from boric acid (H3BO3) at a constant concentration and annealing it at various temperatures (200, 300, and 400 °C). The thin films were formed on glass substrates using the spray pyrolysis process at 250°C, and they were then annealed for two hours in air at various temperatures. It was discovered that the annealing temperature and boron doping had a substantial impact on all properties of the ZnO nanostructure. The polycrystalline hexagonal wurtzite structure is present in both ZnO and BZO thin films. With high optical transmission (≥70%), crystallite diameters of 25.8 to 28.5 nm for ZnO and 15.96 to 24.80 nm for BZO, respectively, and significant absorbance up to 400 nm at the maximum annealing temperature (400 °C) for both films. Moreover, the as-deposited and annealed BZO films had optical band gaps of 3.04 eV and 2.9 eV, respectively, which are less than the ZnO film's 3.23 eV band gap; in general, as the annealing temperature increased it decreased.