Free-Standing Porous Silicon Film Produced by a Pulsed Anodic Etching of n+-Silicon Substrate in an HF: HCl: C2H5 OH: H2O2:H2O Electrolyte: Characterization and Adsorption of Colchicine

Abstract

Porous silicon (PSi) has been established as a promising candidate for a variety of applications in many fields of science and technology. Currently, free-standing PSi is receiving an increasing attention for biomedical applications, such as drug delivery carriers and bio-sensing. In this study, fabrication of free-standing PSi film with attractive structural and optical properties for a prospective biomedical uses, is reported. The film is produced in the dark by a pulsed anodic etching of n+- type silicon substrate in an unconventional (HF: HCl: C2H5 OH: H2O2:H2O) electrolyte. The macro-porous nature of the produced film is revealed by scanning electron microscopy (SEM) imaging. X-ray diffraction (XRD) and Raman scattering investigations show both amorphous and nano-crystalline phases coexist in the produced film. On ageing it for two months, Fourier transformation infrared (FTIR) spectroscopy results reveal that the produced film exhibits the characteristic of efficiently oxidized PSi with a good stability. In addition to the strong S-band, the room temperature photoluminescence (PL) spectrum of the film exhibits a weaker F-band, which is attributed to the recombination in SiO2 allocated at surface defects. Moreover, the film adsorption of colchicine drug via immersion process has been investigated by FTIR and UV-spectrophotometric measurements. The results demonstrate that the colchicine is specifically and efficiently adsorbed, with adsorption capacity of around 33%. The results in this study suggest that our fabricated free-standing PSi film can be effectively utilized to prepare PSi nanoparticles for forthcoming drug delivery applications.