Inverted Pyramidal Porous Silicon by Chemical Etching and PECVD Rebuilding for Selective Gas Sensing
摘要
Nanostructured silicon is a promising material for many recent applications. In this work, inverted pyramidal porous silicon is synthesized by two stages metal assisted etching followed by PECVD rebuilding. At first, nanowires are obtained by conventional Ag assisted chemical etching at the surface of monocrystalline silicon wafer. Then, Inverted pyramidal (IP) macroporous structure is obtained by dipping the sample in HNO3: Ni solution after nanowire harvesting. Finally, PECVD is used to build deep holes on the porous surface template. The depth of the pyramidal holes can be tuned by deposition time and silane pressure. The macroporous structure characteristics are investigated by many techniques such as XRD, SEM, FTIR, reflectivity and impedance. Sensing tests of IP layers for different gases show their selectivity for NO2.