Structural and electrical characterization of Cd-doped ZnO thin films produced on p -type Si substrate by SILAR technique

In this study, undoped and (1%, 3%, 5%) Cd-doped ZnO thin films were produced on p -type Si substrates using the SILAR (successive ionic layer adsorption and reaction) technique at room temperature. The structural properties of both undoped and Cd-doped ZnO films were examined. Surface structural analysis of the fabricated samples was performed using SEM (scanning electron microscopy) and XRD (X-ray diffraction). It was determined that the thin films exhibited a hexagonal wurtzite structure with varying surface morphologies. Moreover, p – n junction diode structures were created using undoped Al/ZnO/ p -Si/Al and %1, %3, %5 Cd-doped Al/Cd:ZnO/ p -Si/Al configurations. The electrical properties of the samples were investigated through current–voltage ( I–V ) and current–time ( I–t ) measurements under different illumination intensities and in the dark. Utilizing the thermionic emission theory, the ideality factor ( n ), barrier height ( Φ b ), and saturation current ( I 0 ) values of the samples were calculated. The results revealed an increase in reverse bias photocurrent with the increment of illumination intensity, indicating the light sensitivity of the samples. Additionally, I – t measurements were evaluated to investigate the photoresponse characteristics of the produced diodes, demonstrating an increase in current with higher illumination intensities. Furthermore, the series resistance ( R s ) values of undoped and Cd-doped ZnO diodes were calculated using the Norde method, revealing values in the order of Ω. Based on the obtained data, it can be concluded that the electrical properties of ZnO diode structures vary with the amount of Cd dopant, and these diodes can be utilized in optoelectronic applications as photodiodes.