The effect of Cu doping on optical and surface properties of ZnO thin films fabricated by thermionic vacuum arc (TVA) deposition

Abstract

In this work, copper as a dopant was utilized in the ZnO thin film, and furthermore the structural, optical, elemental, and topological properties of the films have been carried out upon glass and Si substrates. All coating processes were operated via plasma-based thermionic vacuum arc technology. The mean crystallite sizes of the films were calculated as 78 and 30 nm on glass and Si substrates, respectively. According to the topological results, the RMS value of the films coated onto Si substrate are higher than the film deposited onto glass substrates. The surface images show smooth, compact, and free-crack characteristics of the films. Both films onto the aforementioned substrates have agglomeration. In the optical measurements performed by UV-Vis spectrophotometry, interferometry, and photoluminescence (PL), the refractive indices of the films were 1.63 and 1.82 on glass and Si substrates, respectively. The thicknesses of the films were ascertained as 84 and 80 nm onto the glass and Si substrates. Also, the reflection values of Cu-doped ZnO films were obtained 0.076 and 0.058. These values have revealed the suitability of using the film in the antireflective application. The PL patterns show a defect in the ZnO lattice as well as the shift in the center of the peaks due to copper substitution. The band gap was assessed as 3.17 eV. This narrowing in the band gap value is a demonstration of dopant substitution.