Application of silicon nanoparticles extracted from the Padma river sand of Bangladesh as dopant in metal oxide semiconducting thin films

Abstract

Fabrication of silicon nanoparticles (Si-NPs) from the Padma river sand of Bangladesh by a low-temperature, low-cost, and zero-CO2 emitting process and its application as a dopant in CuO and ZnO have been presented in this article with a motivation to see the influence of locally fabricated Si-NPs on the optoelectronic properties of CuO and ZnO thin films. The sand (SiO2) was reduced using a modified aluminothermic reaction, and leaching with hydrochloric acid (HCL) was used to purify the reaction product to extract > 98% pure Si. After cleaning and drying, the obtained Si powder was ultrasonicated for crushing them into tiny particles of 60–180 nm. The ultrasonicated silicon was further treated with a solution of hydrofluoric acid (HF) and 2-propanol for the etching of the native oxide and passivating the dangling bond with hydrogen (H). Thereafter, highly promising photoactive materials CuO and ZnO were doped with the extracted Si-NPs. Finally, Si-NPs doped CuO and ZnO thin films were deposited on a cleaned glass substrate by spin-coating. X-Ray Diffraction (XRD) confirmed the amorphous nature of Si particles. Dynamic Light Scattering (DLS) demonstrates the size distribution of Si-NPs of ~120 nm for 180 minutes of sonication time. DLS results refer that the higher sonication time offers a lower particle size of Si with controlled rate. The addition of Si-NPs nanoparticles tailors the energy band alignment at the metal oxide/NP interface which provides efficient charge carrier transport and enhanced optical absorption (~20%) as revealed by UV-Vis Spectroscopy. Experimental results indicate that the extracted Si-NPs can be efficiently used in thin-film based optical and electronic devices.