Detection of glucose in water solution for several different concentrations has been performed with the purpose to determine the sensitivity of Near Infrared Bloch Surface Waves (λ = 1.55μm) upon refractive index variations of the outer medium. TE-polarized electromagnetic surface waves are excited by a prism on a silicon nitride multilayer, according to the Kretschmann configuration. The real-time reflectance changes induced by discrete variations in glucose concentration has been revealed and analyzed. Without using any particular averaging strategy during the measurements, we pushed the device detection limit down to a glucose concentration of 2.5mg/dL, corresponding to a minimum detectable refractive index variation of the water solution as low as 3.8·10⁻⁶.

High-electronic quality hydrogenated amorphous silicon-nitrogen (a-Si1-xNx: H) films with an energy gap in the range 1.9-2.7eV have been deposited by plasma-enhanced chemical vapour deposition in silane-ammonia gas mixtures at two different gas residence times and in hydrogen-diluted silane-ammonia gas mixtures. Compositional, structural, electrical and optical properties have been investigated. For the first time the effects of hydrogen dilution of SiH4 + NH3 gas mixtures on the a-Si1-xNx: H network is reported. We have observed that hydrogen dilution decreases hydrogen incorporation and increases nitrogen incorporation, promoting a higher connectivity of the a-Si1-xNx :H network. All films show good electronic properties, comparable with or superior to those of amorphous silicon-carbon films, which are improved in films deposited from hydrogen-diluted gas mixtures

Indium–tin–oxide (ITO) films deposited by sputtering and e-gun evaporation on both transparent (Corning glass) and opaque (c-Si, c-Si/SiO2) substrates and in c-Si/a-Si:H/ITO heterostructures have been analyzed by spectroscopic ellipsometry (SE) in the range 1.5–5.0 eV. Taking the SE advantage of being applicable to absorbent substrate, ellipsometry is used to determine the spectra of the refractive index and extinction coefficient of the ITO films. The effect of the substrate surface on the ITO optical properties is focused and discussed. To this aim, a parametrized equation combining the Drude model, which considers the free-carrier response at the infrared end, and a double Lorentzian oscillator, which takes into account the interband transition contribution at the UV end, is used to model the ITO optical properties in the useful UV–visible range, whatever the substrate and deposition technique. Ellipsometric analysis is corroborated by sheet resistance measurements.

An appreciable increase in the fluorescence emission of an organic chromofore is obtained by exploiting the local field enhancement at the surface of one-dimensional photonic crystals after excitation of surface electromagnetic waves (SEW). Using a properly designed photonic crystal consisting of alternating $a{\text{-Si}}_{1-x}{\text{N}}_x:\text{H}$ layers with different nitrogen content, efficient emission of R6G dye spun on the surface of the photonic crystal is detected and the intensity spatial distribution of the SEW is visualized by means of far-field fluorescence microscopy. Our results demonstrate potential applications in enhanced fluorescence microscopy with an increased sensitivity and spectral selectivity.

$a$ -SiC:H films with energy gap in the range 2.00–2.65 eV have been grown by plasma enhanced chemical vapor deposition in undiluted and ${\mathrm{H}}_2$ diluted ${\mathrm{SiH}}_4+{\mathrm{CH}}_4$ gas mixtures, by making use of optimized deposition conditions. A complete picture of structural, compositional, optoelectronic, and defective properties for high quality films has been drawn for the first time. We show that the addition of ${\mathrm{H}}_2$ to the gas mixture leads to a different chemical composition of the deposited films; in particular, carbon incorporation is enhanced and a carbon fraction in the solid matrix up to C/(C+Si)≈0.45 can be obtained. These films have a higher mass density, a reduced microvoid and carbon cluster concentration, a better structural connectivity, and improved optoelectronic properties. For samples with optical gap below 2.4 eV, the reduced defect concentration of ${\mathrm{H}}_2$ diluted films results in an increase of the photoconductivity gain and the steady-state ${\mathrm{(\eta \mu \tau )}}_{\mathrm{ss}}$ values up to two orders of magnitude.