Facile spray pyrolysis fabrication of Al:CdS thin films and their key linear and third order nonlinear optical analysis for optoelectronic applications

Different quantity of aluminium (Al) doped CdS thin films are fabricated through a facile and cost-effective spray pyrolysis route. Elemental composition and mapping studies approved the presence of Al and its homogeneous distribution throughout the films. The surface morphology of films is found to be modified by Al doping content. X-ray diffraction studies show that the grown films are of hexagonal crystal system. The crystallite size was estimated in range from 16 to 22 nm. Lattice parameters were determined using POWDERX software and confirm single phase of CdS. Vibrational study possesses fundamental phonon modes in all fabricated films related to single hexagonal phase of CdS. Optical study confirms that the films are low absorbing and high transparency. The estimated values of refractive indices are noticed in the range of 1–2.8. Real and imaginary parts of permittivity and loss tangent values were calculated. Furthermore, the linear susceptibility, nonlinear cubic susceptibility, and refractive index were obtained using z-scan technique and observed to be enhanced from 1.17 × 10−6 to 4.66 × 10−6 cmW−1, 3.68 × 10−5 to 6.93 × 10−5 esu. and 2.89 × 10−8 to 5.11 × 10−8 cm2W−1, respectively.