WP10 - JRA5 – Research on Advanced Nano-Object Transfer and Positioning
D10.3 - Methods for deposition of array markers for transfer and position system by laser-based lithography
28 Feb 2018
We fabricated array markers by laser-based direct-write non-linear lithography , which shall permit a controlled deposition of nano-sized objects into ordered patterns and in turn serve to re-localize previously identified nano-objects. The pattern shall be sensitive for tracking by different nanoscience techniques like, e.g., atomic force microscopy (AFM), transmission electron microscopy (TEM), scanning electron microscopy (SEM)  or by the electron- or X-ray excited X-ray fluorescence in an SEM or a nano-focused X-ray beam, respectively.
Here we report that laser-based direct-write non-linear lithography is capable to create line patterns with a lateral line resolution of ~100 nm, and that on these pattern lines can be deposited plasmonic nano-objects, such as gold nanoparticles, and more specifically gold nanorods with a longitudinal axis of 52 nm.
Plasmonic nanostructures has emerged as a promising route to improve light absorption in various optoelectronic devices due to their ability to confine light in spaces of significantly shorter than one fourth of the wavelength of the incident light, thereby providing strong light absorption or scattering. Gold nanoparticles are widely used in many fields as preferred materials for their unique optical and physical properties, such as surface plasmon oscillations for labeling, imaging, and sensing . The peak of the extinction spectra of the NPs occur at the resonant wavelength which highly depends on NPs size, shape, type of metal as well as the local dielectric environment [4,5] . The tunable optical properties along with their strong resonant characteristics make metal NPs attractive for a wide range of applications ranging from biosensing to photovoltaics (PV) [5-10]. Gold nanorods [11–14] have attracted significant attention, due to the ease of preparation, the large number of synthetic methods available, the high monodispersity possible, and the rational control over the aspect ratio, which is primarily responsible for the change in their optical properties. Nanorods have been shown to have two plasmon resonances , one due to the transverse oscillation of the electrons around 520 nm for gold and the other due to the longitudinal plasmon resonance at longer wavelengths. The transverse surface plasmon resonance does not depend on the aspect ratio and is at the same wavelength as the plasmon resonance of spheres. The longitudinal surface plasmon resonance increases with larger aspect ratios.
This work is embedded into the task to develop and to provide user-friendly and easy-to-use platforms for re-localization of small objects like gold nanoparticles, and constitutes one of the two marker strategies that are followed within the framework of the NFFA Joint Research Action “Advanced Nano-Object Transfer and Positioning”. On one hand, the development of hierarchical marker strategies is focusing on several markers of different lateral sizes and thickness values, which shall guide the experimenter towards the pre-selected small object by refining the coordinate system and moving towards the next level of vicinity. On the other hand, we discuss here the successful deposition of single gold nanoparticles onto glass nano-patterned areas, via droplet evaporation of gold nanoparticles’ solution, following proper chemical functionalizaion of the nanopatterns.
The overall goal is to use such substrates with array patterns for deposition of nano-objects like nanoparticles, for a pre-selection of the nanoparticles at the nanoscience centers, by, e.g., SEM, the relocalisation based on the array markers, and a subsequent characterization at the ALSF’s.