Tuning the optical band gap and stoichiometric ratio of chemically synthesized lead selenide thin films by controlling film thickness

Lead selenide (PbSe) thin films with different thickness were deposited by chemical bath deposition method at a bath temperature of 75 °C. The films were synthesized from an aqueous solution of lead acetate trihydrate, ethanolamine, sodium hydroxide and sodium selenosulphate. Structural, chemical composition, optical, and surface morphology of the PbSe thin films were investigated by varieties of techniques to study the influence of film thickness on the material properties. All the as-deposited thin films shows a face centered cubic crystal structure with a preferred orientation along the (200) plan. The XRD results also demonstrated that film thickness had a strong influence on the average crystalline size, texture of coefficients and dislocation density of PbSe thin films. The EDAX study verified that the stoichiometric ratio of the prepared PbSe thin films enhanced as the film thickness increased. The surface roughness of PbSe thin films were examined by atomic force microscopy and it was noticed that root mean square and average roughness increased with film thickness. The optical absorption spectroscopy study revealed that the optical band gap of the PbSe thin films tuned over a wide spectral range by simple and cost effective route from 1.07 eV to 1.50 eV. The photoluminescence study verified that increasing the film thickness enhances the emission intensity and broadens of the emission rang.