A systematic investigation on structural, electrical, linear and nonlinear optical properties of Zn:CdO thin films for optoelectronic applications

Abstract

In the present work, a systematic study on structural, electrical, linear, and nonlinear optical properties of Zn doped CdO thin films prepared by Spray Pyrolysis (SP) technique is reported. X-ray diffraction (XRD) studies revealed the cubic, wurtzite structure, and polycrystalline nature of all the films. The observed results showed a decrease in lattice constant and unit cell volume with an increase in Zn doping concentration. Morphology study confirms uniform distribution of spherical grain-like structure with small voids. An increase in direct and indirect bandgap is observed with doping concentration up to 5 wt%, and the trend reverses at higher concentration. The significant effect of Zn doping on optical parameters such as absorption coefficient, extension coefficient, refractive index, optical dielectric constant, and optical conductivities are calculated for all thin films. Further, the optical studies were used to analyze the linear susceptibility, third-order nonlinear optical susceptibility, and nonlinear refractive index of the films. The observed values for χ(1),χ(3) and n2 are in the range from 0.03 to 0.09 esu, 3.51×10−16 to 1.02×10−14 esu, and 1.09×10−14 to 2.67×10−13 esu for pure and Zn doped thin films respectively. Hall coefficient and electrical studies indicate that the Zn doping influences the electrical properties. An n-type and ohmic behavior is also observed for these films. Optical and electrical results suggest that these Zn:CdO films can be a potential candidate for optoelectronic applications.