Electron-beam-induced deposition (EBID) is a gas-phase direct-write technique capable of sub-10 nm resolution, with applications in micro- and nanoscale object manipulation, mask repair, and circuit edit. While several high purity materials can be deposited by EBID, the majority of deposits suffer from undesirable co-deposition of organic or inorganic ligands. As a result, impurity incorporation limits EBID application in processes requiring high purity. Recently, a complimentary technique known as liquid phase EBID (LP-EBID) has been shown to drastically improve deposit purity by utilizing precursors without carbon or phosphorous based architectures. Here we demonstrate direct-write deposition of silver nanostructure arrays, with tunable geometry for localized surface plasmon resonance (LSPR) control. Nanoparticle arrays with 55 – 100 nm diameters were obtained. Resonant wavelengths between 550 - 600 nm were achieved and correlated to the observed nanoparticle geometry. These results demonstrate how LP-EBID can be used to provide site-specific deposition for plasmonic devices and additionally open the door to fields inaccessible to traditional gas-phase EBID.
Noble metal nanoparticles supporting localized surface plasmon resonances (LSPR) have been extensively investigated
for label free detection of various biological and chemical interactions. When compared to traditional propagating
surface plasmon based sensors, LSPR sensors offer extensive wavelength tunability, greater electric field enhancement and sensing in reduced volumes. However, these sensors also suffer from a major disadvantage – LSPR sensors remain
highly susceptible to interference because they respond to both solution refractive index changes and non-specific
binding as well as specific binding of the target analyte. These interactions can compromise the measurement of the target analyte in a complex unknown media and hence limit the applicability and impact of the sensor. Despite the
extensive amount of work done in this field, there has been an absence of optical techniques that make these sensors
immune to interfering effects. Recently, our group experimentally demonstrated a multi-mode LSPR sensor that exploits
three resonances of a U-shaped gold nanostructure to differentiate the target interaction from bulk and surface interfering
effects. In this paper, we provide a comprehensive description of the electric field profiles of the three resonances of the U-shaped nanostructure. We will also evaluate the sensitivities of the nanostructure to the various bulk and surface interactions using numerical simulations.