A composite material of plasmonic nanoparticles embedded in the scaffold of nanoporous Silicon offers unmatched capabilities to use it as a SERS substrate. The marriage of these components presents an...

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Coupling between nanoplasmonics and semiconducting materials can enhance and complement the efficiency of almost all semiconductor technologies. It has been demonstrated that such composites enhance the light coupling to nanowires, increase photocurrent in detectors, enable sub‐gap detection, allow DNA detection, and produce large non‐linearity. Nevertheless, the tailored fabrication using the conventional methods to produce such composites remains a formidable challenge. This work attempts to resolve that deficiency by deploying the immersion‐plating method to spontaneously grown gold clusters inside nano‐porous silicon (np‐Si). This method allows the fabrication of thin films of np‐Si with embedded gold nanoparticles (Au) and creates nanoplasmonic–semiconductor composites, np‐Si/Au, with fractional volume between 0.02 and 0.13 of the metallic component. Optical scattering measurements reveal a distinctive, 200 nm broad, localized surface plasmon (LSP) resonance, centered around 700 nm. Linear and non‐linear properties, and their time evolution are investigated by optically pumping the LSP resonance and probing the optical response with short wavelength infra‐red (2.5 μm) light. The ultrafast time‐resolved study demonstrates unambiguously that the non‐linear response is not only directly related to the LSP excitation, but strongly enhanced with respect to bare np‐Si, while its strength can be tuned by varying the metallic component.

Tailoring of the cytotoxicity and dissolution rate of luminescent porous silicon quantum dots is presented.

Biodegradable porous silicon (pSi) particles are under development for drug delivery applications. The optimum particle size very much depends on medical use, and microparticles can outperform nanoparticles in specific instances. Here we demonstrate the ability of sedimentation to size-select ultrasmall (1–10 μm) nanoporous microparticles in common solvents. Size tunability is quantified for 1–24 h of sedimentation. Experimental values of settling times in ethanol and water are compared to those calculated using Stokes’ Law. Differences can arise due to particle agglomeration, internal gas generation and incomplete wetting. Air-dried and supercritically-dried pSi powders are shown to have, for example, their median diameter d (0.5) particle sizes reduced from 13 to 1 μm and from 20 to 3 μm, using sedimentation times of 6 and 2 h respectively. Such filtered microparticles also have much narrower size distributions and are hence suitable for administration in 27 gauge microneedles, commonly used in intravitreal drug delivery.