Passivation of nanostructured silicon optical devices by thermal carbonization

Nanostructured silicon interference filters have been thermally carbonized by acetylene decomposition at different temperatures in order to passivate their high internal surface area. Stability has been studied by periodically measuring the optical spectrum of treated and untreated porous silicon filters stored in oxidizing environments. Experimental results show that thermal carbonization stabilizes the structures against oxidation, since treated samples show no significant shift of their optical spectra after storage in either ambient air or ethanol for up to two months. Moreover, the thermal carbonization process has no significant effect on the optical performance of the filters. Results show that thermal carbonization by acetylene decomposition provides an effective way to produce chemically stable porous silicon optical devices for biological and chemical sensing. (C) 2007 Elsevier Inc. All rights reserved.