Enhanced electro-optical properties of CdS thin films through Sb nanosheets coating

Cadmium sulfide thin films are deposited using the thermal evaporation technique and coated with 50 nm thick Sb nanosheets. Both the coated and uncoated films undergo structural, morphological, and optical investigations to explore potential modifications resulting from the Sb coating. The antimony nanosheets successfully increase the crystallite sizes from 28 to 34 nm and decrease the defect concentration from 4.36 × 10¹¹ lines/cm² to 3.02 × 10¹¹ lines/cm². The deposition of Sb nanosheets on CdS films induces the formation of nanowires with a length of 3.0 μm. Sb nanosheet coatings improve visible light absorption by more than nine times, redshift the energy band gap, suppress free carrier absorption in the infrared (IR) range, and increase the optical conductivity of CdS films. Additionally, as optical filters and waveguides, Sb-coated CdS films exhibit a terahertz cutoff frequency range of 0.47–32.06 THz as light energy increases from the IR to ultraviolet ranges. It is also observed that Sb coating alters the third-order nonlinear susceptibility of CdS, making it tunable, more polarizable, and suitable for nonlinear optical applications. Photocurrent measurements showed that Sb nanosheets improved the light responsivity by 330% and significantly enhanced the response time. The enhanced features of CdS achieved through Sb nanosheet coatings position CdS in the preferred group for nonlinear optical waveguides applicable in terahertz and nonlinear optical applications.