Abstarct: Ultraviolet detectors baxsed on zinc oxide (ZnO) are considered promising systems in the field of optoelectronic devices due to their wide direct band gap, high exciton binding energy, and good chemical stability. However, achieving high sensitivity and a large on/off ratio with a short response time remains an important research challenge. In this study, five ZnO thin film samples were prepared using the sol–gel technique; including one pure sample and four samples doped with calcium chloride at concentrations of 1%, 2%, 4%, and 8%. The effect of doping and preparation conditions on the structural, morphological, optical, and electrical properties was investigated. XRD and FESEM analyses showed that doping improved crystallinity, controlled grain size, and reduced grain agglomeration. DRS and PL measurements also demonstrated the ability to tune the band gap and reduce surface recombination centers. In addition, Raman spectra were analyzed to confirm the crystal structure and to study the changes resulting from calcium doping. Measurements of the change in resistance of the photodetectors under ultraviolet illumination and in darkness showed a significant improvement in reducing the photoresponse time at the higher doping ratio (8%) compared with the undoped sample, whereas longer response times were observed at lower doping ratios. The results of this thesis provide a scientific basis for the development of high-efficiency and low-cost ultraviolet detectors baxsed on sol–gel prepared ZnO.