Study of CdS/CdS Nanoparticles Thin Films Deposited by Soft Chemistry for Optoelectronic Applications

Chalcogenides semiconductors are currently being studied as active layers in the development of electronic devices in the field of applied technology. In the present paper, cadmium sulfide (CdS) thin films containing nanoparticles of the same material as the active layer were produced and analyzed for their application in fabricating optoelectronic devices. CdS thin films and CdS nanoparticles were obtained via soft chemistry at low temperatures. The CdS thin film was deposited via chemical bath deposition (CBD); the CdS nanoparticles were synthesized via the precipitation method. The construction of a homojunction was completed by incorporating CdS nanoparticles on CdS thin films deposited via CBD. CdS nanoparticles were deposited using the spin coating technique, and the effect of thermal annealing on the deposited films was investigated. In the modified thin films with nanoparticles, a transmittance of about 70% and a band gap between 2.12 eV and 2.35 eV were obtained. The two characteristic phonons of the CdS were observed via Raman spectroscopy, and the CdS thin films/CdS nanoparticles showed a hexagonal and cubic crystalline structure with average crystallite size of 21.3-28.4 nm, where hexagonal is the most stable for optoelectronic applications, with roughness less than 5 nm, indicating that CdS is relatively smooth, uniform and highly compact. In addition, the characteristic curves of current-voltage for as-deposited and annealed thin films showed that the metal-CdS with the CdS nanoparticle interface exhibits ohmic behavior.

Automated summary

Chalcogenides semiconductors, such as cadmium sulfide (CdS), have potential applications in optoelectronic devices. This study focuses on the synthesis and analysis of CdS thin films and CdS nanoparticles. The CdS thin films were deposited using chemical bath deposition, while the CdS nanoparticles were synthesized via the precipitation method. The CdS nanoparticles were incorporated on the CdS thin films to form a homojunction. The resulting modified thin films exhibited good transmittance, with a band gap between 2.12 eV and 2.35 eV. Raman spectroscopy confirmed the hexagonal and cubic crystalline structure of the CdS thin films/CdS nanoparticles, with an average crystallite size of 21.3-28.4 nm. The interface between the CdS nanoparticles and metal exhibited ohmic behavior.