Role of deposition temperature on non-linear optical properties of spray-coated Zn_0.95Nd_0.05O films

The influence of deposition temperature on the structure and optical (linear and nonlinear) properties of Zn_0.95Nd_0.05O thin films grown on glass substrates by using the spray pyrolysis method is studied. The X-ray diffraction spectra reveal the hexagonal wurtzite structure with a reduction in peak intensity as deposition temperature increases. With increasing temperature, the prominent peak intensity changes, and the dislocation density increases. Concomitantly, the surface morphology transitions from a nanoflake to a needle-like structure. With increasing deposition temperature, the optical transmittance of the films in the visible region improves, while the energy bandgap, refractive index and extinction coefficient values decrease. The reduction of refractive index and extinction coefficient values is ascribed to decreased scattering and uniformity of the films. Further, the films exhibit saturable absorption and films deposited at 300 ℃ show a maximum for third-order nonlinear susceptibility, which is quite appealing for nonlinear optical devices and components.