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Porous silicon microcavity resonators possess the unique characteristics of line narrowing and luminescence enhancement. The emission peak position is completely tunable by changing the properties of the central layer. Increasing the thickness of the central active layer introduces multiple narrow peaks in the luminescence spectrum. Narrow and visible luminescence peaks are observed with a full width at half the maximum (FWHM) value of 3 nm. The microcavity structure is highly sensitive and any slight change in the effective optical thickness modifies the reflectivity spectra, causing a spectral shift in the interference peaks. This makes porous silicon microcavities an ideal host for sensor applications. We demonstrate the usefulness of this microcavity resonator structure as a biosensor. A DNA biosensor has been fabricated based on a porous silicon multiple peak microcavity structure. Shifts in the luminescence spectra are observed and detected for various DNA concentrations. When exposed to a non-complementary DNA strand, no shifts are observed. An extension of the DNA biosensor has been made to include the detection of viral DNA. Both sensor fabrication and results of extensive testing are presented in this report.
Chan et al. (Wed,) studied this question.