Investigation of the surface, morphological and optical properties of boron– doped ZnO thin films deposited by thermionic vacuum arc technique

Abstract

In this study, boron—doped ZnO (ZnO:B) thin films have been deposited on amorphous glass and polyethylene terephthalate (PET) substrates by thermionic vacuum arc (TVA) technique. The surface, morphology, microstructure, optical properties, and chemical analysis of B doped ZnO thin films were investigated. To determine the subjected properties, atomic force microscopy (AFM), field emission electron microscopy (FESEM), x–ray diffraction (XRD), UV–Vis spectrophotometer, Raman and Fourier transform infrared spectroscopy measurements have been carried out. The thicknesses values of the films were measured as to be 50 nm and 60 nm on glass and PET substrates. XRD results show that polycrystalline nature of the deposited thin films on the PET substrate is higher than the deposited films on glass substrate. All films are in polycrystalline structure. The deposited thin films are including ZnO crystalline formations. According to the Scherrer’s formula, the crystallite sizes were calculated approximately 20 nm for ZnO crystallites. Atomic force microscopy and field emission electron microscopy images revealed the formation of fine—dispersed, homogeneous, uniform and granular structure on the surface of the films. Optical studies show that the average transmittance values of the ZnO:B films were obtained to be 62% and 83% on glass and PET substrates, respectively. The mean refractive index of the films also obtained as 1.69 and 1.65 on glass and PET substrate, respectively. In order to the Tauc’s relation and photoluminescence measurements, the optical band gap values of the boron doped films were found to be 3.2 and 3.3 eV on glass and PET substrates, respectively. Raman spectra are also support the boron doped ZnO structures deposited onto glass and PET substrate.