This thesis reports on the experimental examination of the use of nanostructures for three topics of light-matter interaction.
First, enhanced photon absorption for photocatalytic reactions has been demonstrated. Photocatalytic metal nanoparticle synthesis is of significant interest in plasmonic biosening due to the simple fabrication capability. However, long synthesis time of more than 10 hours and the use of particle stabilization chemical agents hinder economical and rapid synthesis of such metal nanoparticle systems. We demonstrate a Si subwavelength nanostructure-based photochemical device. We show rapid photocatalytic structure transformation of noble metal nanoparticle ionization and reduction within 5 minutes with only pure water and room light illumination.
Second, 3D nanostructures for optical biosensing have been investigated. We demonstrate optical spectroscopy by using subwavelength dielectric nanostructures as the substrate material for localized surface plasmon resonance metallic nanoparticles. Nanostructured substrates made of Si and Si3N4 have been characterized and compared. Schemes of enhancing the optical signal extraction are also discussed. We show the potential of dielectric based nanostructure substrate for applications in optical molecular sensing.
Third, the experimental approaches from the two demonstrations are merged for photocatalytic nanoparticles. TiO2 nanoparticles are formed along the sidewall of subwavelength Si nanostructure. The dual semiconductor system is investigated for photocatalytic bacteria disinfection in water. We show disinfection of E. coli with just room light illumination on our proposed device. Possibilities of extending this device towards water splitting are also discussed.
Each application is introduced with a brief motivation, description of the experimental method, and discussion of the results. Possible future directions are also presented
