Investigation on nebulizer spray deposited Gd-doped PbS thin films for photo sensing applications

Nebulizer assisted spray technique has been implemented for the deposition of pure and gadolinium (Gd) doped PbS thin films at a substrate temperature of 210 degrees C onto glass substrate using lead nitrate and gadolinium (III) acetate as precursors. Doping percentage of Gd was varied from 0 to 5 wt% for the preparation of Gd doped films and to analyze the film property. A variety of techniques like X-ray diffraction, Raman spectrum, scanning electron microscopy, atomic force microscopy, energy dispersive X- ray, UV-Visible spectrometer, and keithley source meter were used to study the influence of Gd doping in PbS thin films X-ray diffraction revealed no change in preferential orientation of the crystal planes without any secondary phases formed for all the Gd-doped films. And also it confirmed that the nature of the films were polycrystalline with simple cubic structure. It also further confirmed polycrystalline simple cubic structure with decrease of crystallite size from 21 nm to 16 nm for the increase of gadolinium doping concentration from 0 to 5 wt%. Noticeable change in the grain size was observed for the 5 wt% of gadolinium doping with uniformly distributed spherical shaped nanosize grains fully covering the entire surface. The compositional analysis confirmed the presence of Pb, S and Gd in the films. The optical parameters of Gd doped PbS thin films such as band gap energy, refractive index; extinction co-efficient, and real and imaginary parts of dielectric constant were determined using transmission, absorption and reflectance spectra in the range of 300-2400 nm. A maximum value of photo current was observed for 5 wt% gadolinium doped film.