Effect of the Porosity of a PSi Substrate on the Characteristics of CdS Nanoparticles Produced by the CBD Method

Abstract

The motivation for research to study the potential offered by semiconductor materials such as silicon is their use as a substrate for the manufacture of thin films. In this work the chemical bath deposition (CBD) method was used to synthesize Cadmium sulphide (CdS) thin films on glass, silicon (Si), and porous silicon (PSi) substrates. The PSi substrates were prepared by an electrochemical etching method using different current densities at constant etching time of 5 minutes. The obtained results demonstrated that the morphology of the deposited materials was influenced by the porosity of the PSi substrates. The average crystallite dimensions for CdS/glass and CdS/Si were determined to be 46.12 nm and 23.08 nm, respectively. In CdS/PSi structures, the average value of the grain size decreases with increasing porosity. The smallest one is obtained for the CdS/PSi structure with 70% porosity, amounting to 11.55 nm. The measured current-voltage characteristics in coplanar structure on the CdS/PSi/Si sample showed that the photocurrent of the CdS/Si structure is of 3.17 µA and increases up to 600 µA for the CdS/PSi/60% structure.