Carbonization of porous silicon optical gas sensors for enhanced stability and sensitivity

Abstract

Nanostructured porous silicon (PS) optical filters have been widely proposed for their use in biological and chemical sensing applications. Porous silicon, however, presents a reactive surface that must be adequately passivated in order to achieve the required chemical stability mandatory for sensing applications. In the present work, thermal carbonization by acetylene decomposition (TCAD) is shown to provide sivation of PS internal surface, as well as an enhancement of the device's sensitivity to certain species. Moreover, it is shown that the TCAD process, as opposed to more common oxidation treatments, has only minor effects on the optical properties of PS. Thus, the optical performance of PS interference filters is preserved after the carbonization process.