Abstract

Porous silicon (PS) is a sponge-like structure of silicon with a high surface to volume ratio and properties that distinguish it from bulk silicon. The structure is suitable for many applications such as biosensors, optoelectronic, drug delivery and solar cell devices. Although there are many reports available in the literature regarding the PS and its application but there is no work done systematically to investigate the fabrication of the PS for various applications. In this work we are investigating the PS production under various fabrication conditions. This work produces instructions to fabricate PS structures for any specific application. We have used electrochemical technique to fabricate samples of PS and undertaken studies the effects of several physical parameters like, materials doping level, light illumination, etching time, applied electric current and silicon surface defects, and chemical parameters like, impurities, and PH factor of the electrolyte during the PS preparation. In order to investigate the effect of silicon surface defects some textured surfaces of silicon samples were prepared by anisotropic etching of silicon in TMAH prior to their electrochemical etching in HF solutions. Structures were characterized using SEM, AFM and Raman spectroscopy. For the first time, fabricated pyramidal porous silicon was used to prepare granular metallic films using electrodeposition techniques. We have also used the pyramidal porous structures to fabricate a miniaturized gas ionization sensor (GIS). GIS works based on measuring the breakdown voltages for various gases. The sensor was fabricated using a parallel plate model having PS as one of the electrodes.