Nickel content effect on the microstructural, optical and electrical properties of p-type Mn3O4 sprayed thin films

Nickel doped Mn3O4 thin films have been prepared by the spray pyrolysis method on glass substrates at 350 °C. X-ray diffraction and Raman spectroscopy studies revealed that all deposited films were polycrystalline with tetragonal husmannite Mn3O4 structure. From the reflectance and transmittance optical measurements, it is found that the direct band gap energy exhibits a red shift from 2.23 to 1.87 eV with Ni doping. On the other hand, the Hall measurements show that all films exhibit p-type conductivity and this character is reinforced when Ni content increases. Moreover, AC conductivity measurements lead to a power low (σAC = Aωs). The dependence of both σAC and s with temperature and frequency agrees well with the CBH model as suggested by Elliott.