Performance evaluation of SILAR deposited Rb-Doped ZnO thin films for photodetector applications

ZnO-based photodetectors (PDs) compose a remarkable optoelectronic device field due to their high optical transmittance, electrical conductivity, wide band gap, and high binding energy. This study examined the visible light photodetector performance of the pristine and Rubidium (Rb)-doped ZnO thin films. The influence of Rb doping amount (2, 4, and 6 wt% in solution) on the electrical, optical, and structural properties of the ZnO-based thin films produced by the Successive Ion Layer Adsorption and Reaction (SILAR) technique was analyzed. Structural analyses showed that all peaks correspond to hexagonal wurtzite structure with no other peak from Rb-based phases, suggesting the high quality of the crystalline pristine and Rb-doped ZnO thin films. The morphology of the thin films shows homogenous layers formed of nanoparticles where particle size was first decreased and then increased with the increasing Rb doping according to Scanning Electron Microscope (SEM) morphology analysis. Besides that, Raman spectroscopy analyses indicate that the phonon lifetimes of the ZnO-based thin films slightly increased due to the improvement of the crystal quality with the increasing amount of Rb in the SILAR solution. Photosensor measurements of the nanostructured pristine and Rb-doped ZnO thin films were measured at different light power intensities under the visible light environment. Photosensor properties were examined depending on the doping amount and light power density. In light of the literature review, our study is the first to produce Rb-doped ZnO thin films via the SILAR method, which has a promising potential for photosensor applications. The effect of Rb doping (2, 4, and 6 wt%) on the structural, optical, and photocurrent properties of the ZnO-based thin films.The Rb-doped ZnO thin films produced via the SILAR method consist of hexagonal wurtzite structures without any secondary phase and with nanoscale grain formations for different amounts of Rb doping.The responsitivity of Rb2:ZnO, Rb4:ZnO, and Rb6:ZnO were calculated 0.1532, 0.344, and 5.56, respectively.The EQE values were calculated 0.05%, 0.20%, 0.47%, and 7.61% for ZnO, Rb2:ZnO, Rb4:ZnO, and Rb6:ZnO, respectively.