Evaluation of structural and optical properties of Mn-Doped ZnO thin films synthesized by Sol-Gel technique

Abstract

Undoped ZnO and Mn-doped ZnO (MZO) films with 0.25, 0.50, and 0.75 mol pct were synthesized onto glass substrates by sol-gel spin-coating technique, and the effects of Mn on structural, morphologic, and optical properties were investigated. the XRD results indicate that the films have wurtzite structure with polycrystalline nature. However, the dominant peak was (002) diffraction peak for all samples; other diffraction peaks with less intensity such as (100), (101), (102), (110), (103), (112), and (004) were observed for the undoped ZnO. the lattice parameter values of MZO thin films were lower than that of the undoped ZnO. Plane stress values indicated that the films had the tensile stress. A decrease in the grain sizes was observed with the increasing Mn mole percent. the optical transmission values were found to be 82 pct for the undoped ZnO and 80, 78, and 75 pct for the MZO with 0.25, 0.50, and 0.75 mol pct, respectively, at the wavelength of 405 nm. the optical band gap values decreased from 3.287 to 3.270 eV, the surface roughness values increased from 58.13 to 60.67 nm, Urbach energy values increased-a 18.3-meV difference in Urbach energy was observed-and in addition, the steepness parameters decreased with increasing Mn content from 0 to 0.75 mol pct.