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Proceedings Paper

Porous silicon optical sensors for vapors, liquids, and biological molecules
Author(s): Luca De Stefano; Ivo Rendina; Luigi Moretti; Andrea Mario Rossi; Annalisa Lamberti; Olimpia Longo; Paolo Arcari
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Paper Abstract

Recently, an increasing interest has been devoted to the use of porous silicon (p-Si) in photonics and in sensing fields. In particular, the great reactivity, mainly due to its large surface to volume ratio, has demonstrated to be promising in sensing applications for the detection of gases, vapors, and biochemical molecules. In this work, we present experimental and numerical results on p-Si optical microcavities as sensing transducers in biological and chemical fields. The measures are based on the change of the cavity reflectivity spectrum induced by the exposition to the bio-chemical specimen under test. The p-Si microcavity has a Fabry-Pèrot structure confined between two Distributed Bragg Reflectors (DBRs) with high reflectivity in the wavelength range of interest. The DBRs have been obtained modulating the porosity, therefore the refractive index, of p-Si layers during the silicon electro-chemical etching process. The optical thickness (nd) of each single-layer forming the DBR is l/4, where d is the layer physical thickness, n its refractive index and l is the Bragg wavelength. A l/2-thick layer placed between the top and bottom DBRs works as a microcavity resonating at the Bragg wavelength l. The realized sensors operate at the fiber optic communication wavelength of 1.55 mm. A complete experimental characterization of the devices as vapor and liquid sensor is reported. An analytical model, allowing the correct interpretation of the sensing dynamics, is also reported and discussed. Finally, preliminary results concerning DNA-probe immobilization in p-Si pores and consequent recognition of complementary DNA strands are presented.

Paper Details

Date Published: 29 April 2003
PDF: 5 pages
Proc. SPIE 5118, Nanotechnology, (29 April 2003); doi: 10.1117/12.498999
Show Author Affiliations
Luca De Stefano, IMM-CNR (Italy)
Ivo Rendina, IMM-CNR (Italy)
Luigi Moretti, Univ. della Calabria (Italy)
Andrea Mario Rossi, Istituto Elettrotecnico Nazionale Galileo Ferraris (Italy)
Annalisa Lamberti, Univ. di Napoli Federico II (Italy)
Olimpia Longo, Univ. di Napoli Federico II (Italy)
Paolo Arcari, Univ. di Napoli Federico II (Italy)

Published in SPIE Proceedings Vol. 5118:
Robert Vajtai; Xavier Aymerich; Laszlo B. Kish; Angel Rubio, Editor(s)

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