Formation and characterization of silver nanoparticles embedded in optical transparent materials for plasmonic sensor surfaces

Abstract

• We analyzed particle forming behavior of thin Ag seed films before/after annealing. • We examined passivation layers produced via different deposition methods. • Ag particles embedded in Al 2 O 3 films were tested as LSPR-sensor-surface. • LSPR shifted 6.15 nm for a refractive index change of 0.07 using glucose solutions. Plasmonic nanostructures promise sensing capabilities with the potential for ultrasensitive and robust assays in life sciences and biomedicine. Silver island films represent an interesting and straightforward alternative for the implementation of substrate-attached plasmonic nanostructures. The temperature-induced particle-forming behavior of thin silver seed films deposited on glass substrates and on polycrystalline silicon films is represented. The measured extinction spectra reflect the different size distributions and shapes. The covering of the particles with different optical transparent film materials like ZnO, Al 2 O 3 , SiN x , and SiO x leads to a further shift in the resonance maximum due to their refractive index. The SiO x system shows an additional long term change in the extinction spectrum in contrast to ZnO, Al 2 O 3 , and SiN x . Thin silver films covered with Al 2 O 3 were used in order to proof the system as a sensor element for analyte detection (glucose solution).