Structural considerations on multistopband mesoporous silicon rugate filters prepared for gas sensing purposes

Institute of Advanced Energy, Kyoto University, Uji, Kyoto, Japan.
Optics Express (Impact Factor: 3.49). 07/2011; 19(14):13291-305. DOI: 10.1364/OE.19.013291
Source: PubMed


Different designs for producing multiple stopband mesoporous silicon rugate filters via electrochemical anodization are compared. The effects of light absorption and dispersion to visible range filter design are investigated. Thermal oxidation is applied for passivating the chemically reactive porous silicon surface, and the response of the passivated structures to ethanol vapor is examined. Differences in gas sensing properties for the various designs are evaluated and possible reasons for the observed differences are discussed. Methods for sidelobe suppression in multipeak filters are discussed and demonstrated, and their effects in gas sensing applications are estimated.

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    • "Figure 6 shows a reflectivity spectrum and a backscatter SEM image of two separate rugate structures etched on top of each other. It has to be emphasized that the stacking order of the rugate filters is important for the appearance of both rugate peaks in the reflectivity spectrum [46]. "
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