Enhancement of dielectric properties of Ni and Co doped ZnO due to the oxygen vacancies for UV photosensors application

In our study, Zn_1-xM_xO (M = Ni, Co) were elaborated by a facile route polyol process. We used the impedance spectroscopy to find the impacts of temperature, frequency and oxygen vacancies on both dielectric and transport properties of our samples. We concluded that both the electrical and dielectric performances were related to the oxygen vacancies. Then, a colossal dielectric constant up to 4100 and a low dielectric loss of 0.2 have been found in Co doped ZnO Nps and it is a very high permittivity values as compared to other material oxides. That is why, reflectance diffuse and electric modulus spectroscopy are used to study the origin of this high permittivity. Furthermore, the electrical performances were characterized by current-voltage (I-V) under dark and light illumination. These important electrical and dielectric results obtained for the Co doped ZnO Nps make them interesting material for use in UV photodetector that require high dielectric constant.