Preparation of self-powered bilayer Co–ZnO/ZnO UV photodetector

Wide-bandgap metal oxide materials such as ZnO are critical for optoelectronic applications. In this study, self-powered devices with the ITO/(Co-ZnO)/ZnO/Ag structure have been fabricated using cobalt doped and undoped ZnO thin films. According to the Hall effect results, the carrier concentrations of the samples varied between 7.14×10 18 cm -3 and 2.94×10 19 cm -3 . With the addition of cobalt, the resistivity of the samples increased, and the mobility decreased. These prepared devices show high sensitivity to UV light. The photosensitivity of these devices, which operate under UV light without any external voltage, reaches a high value of ∼ 3.4×10 4 . Moreover, the photoresponsivity and specific detectivity values are 0.27 mA.W -1 , and 7.4×10 9 Jones. The effect of heat treatment in air and vacuum environment on device performance was also investigated, and a significant improvement was observed in the performance of samples annealed in vacuum environment. Annealing in a vacuum environment increases the sensitivity of the devices by 12465 %. • Highly sensitive bilayer Co-ZnO/ZnO UV photodetectors were prepared. • The photodetectors show ∼ 3.4×10 4 sensitivity to UV light. • Annealing in a vacuum environment increases the sensitivity of the devices by 12465%.