Spray pyrolysis deposited K@CdS nanostructured films and their characterizations for optoelectronic and 3rd order nonlinear optical applications

Abstract

Cadmium Sulfide (CdS) is an excellent semiconductor for photonic devices and its optical and electrical properties are greatly affected by single element doping. In the current manuscript, the effect of potassium ion (K+) doping on linear and nonlinear optical traits of spray pyrolysis deposited CdS films was investigated. The X-ray diffraction (XRD) spectra reveal the increase of defects, decrease of crystallinity and crystallite size also change in growth orientation with K+ doping in CdS films. Moreover, the position of FT-Raman peaks was slightly blue shifted and morphology of films shows clusters of agglomerated CdS nanoparticles along with small size nanoparticles in the background as revealed from SEM images. The bandgap of K+-doped CdS films slightly broaden and shows improved transparency as compare to pure CdS films. The dielectric constants were found to be first decease for 2.5% wt. K+ doping and thereafter slightly increase for 5.0% wt. CdS films whereas optical conductivity decrease for all K+ doping concentrations. The photoluminescence intensity of CdS decreases and slightly blue shifted upon K+ doping, also a new emission band appears at 630 nm, indicating formation of new trap states in the bandgap of semiconductor. The 3rd order nonlinear properties elucidated through Z-scan technique reveals the increase of n2 and χ3 whilst decrease of β with increase of K+ content in CdS thin films.