Infiltration of carbon-silicon composites into porous silicon by an electrochemical method

An alternative method to infiltrate carbon-silicon composites into a porous silicon (PS) matrix via electrochemical etching of crystalline silicon (1 0 0) wafers is presented. This is a novel technique used to infiltrate carbon in situ into PS and to form silicon-carbon composites during the same process. An electrolytic base consisting of ethanol and hydrofluoric acid (HF:EtOH) was used to make the samples. Different infiltration procedures were carried out with a source of carbon. Graphene oxide (GO) or graphite powder were used as the carbon source in the electrolyte, which was used to etch crystalline silicon, from which carbon-silicon composites ensued. The carbon source was added at the tips or all along the crystalline silicon etching. GO was obtained from commercial graphite by the improved method of Hummer. The experimental method involves the modification of the electrolyte to determine if porous silicon can be created and then infiltrated by carbon during formation. The structural, morphological, and optical properties of the samples were characterized by X-ray diffraction (XRD), Raman spectroscopy, scanning electron microscopy (SEM), and photoluminescence (PL). Si, C, and O atoms were mapped by energy-dispersive X-ray spectroscopy (EDS). The results show that PS can be fabricated by using a carbon source in the electrolyte, and that a carbon-silicon composite is also formed and deposited into the PS matrix rather than on the surface. The characterizations showed that the carbon source influences the structural, morphological, and optical properties of the samples.