Structural, electrical, linear and nonlinear optical analysis of the innovative n-type ZnV2O4 thin films synthesized by spray pyrolysis

This work presents an extensive study of the optical, morphological, structural, and electrical characteristics of ZnV2O4 thin films that were generated by spray pyrolysis for first time. In the present investigation, the X-ray diffractometer (XRD) structural analysis confirmed that the ZnV2O4 thin film developed as a single phase featuring a cubic crystallographic structure. Based on reflectance and transmittance data, the ZnV2O4 films showed a direct optical transition with a band gap range from 3.15 to 2.89 eV as the thickness varied between 238 and 549 nm. This work focused on studying the relationship between thickness and optical parameters, including extinction coefficient (k), refractive index (n), optical dielectric constants (epsilon 1, epsilon 2), and Urbach energy (Eu), which were thoroughly examined. The increase in thickness improves the nonlinear optical values, such as the nonlinear refractive index and susceptibility (chi(1), chi(3)). The electrical properties of ZnV2O4 thin films were studied by measuring the DC conductivity and the current-voltage characteristics of these ZnV2O4 samples. The analysis of the DC conductivity of these ZnV2O4 samples revealed that a decrease in the activation energy occurred by growing the thickness from 238 to 549 nm. The n-type conductivity of the ZnV2O4 samples was seen from the hot probe experiment. The obtained results indicated that the ZnV2O4 films could act as a promising window layer for thin-film solar cells, and as a promising candidate in optoelectronic applications.