Ordered Nanotrees Fabrication for SERS Sensing

The fabrication process is segmented into distinct stages: forming alternating nanosheet layers with different etch properties, patterned etching to create trunk sections, and selective removal to form branches. Each stage produces a specific structural component with predetermined dimensions, enabling precise control over the final nanotree geometry while maintaining systematic process management

Different regions of the nanotree structure are created with locally optimized properties through selective etching. The trunk sections have different thicknesses and the branches have varying widths and spacing, all predetermined during fabrication. This local differentiation enables optimization of plasmonic resonance characteristics for specific sensing applications while maintaining overall structural precision

The nanosheet layers are deposited with predetermined thicknesses and etch properties before the etching process begins. The alternating layers are prepared in advance with specific material compositions that respond differently to etching, allowing the complex three-dimensional nanotree structure to self-form during the etching process rather than requiring complex post-fabrication assembly steps

The fabrication method controls multiple parameters simultaneously: nanosheet thickness, etch selectivity ratios, pattern dimensions, and layer composition. By adjusting these parameters, the nanotree structure's trunk thickness, branch width, branch spacing, and overall geometry can be predetermined and optimized for specific sensing applications like SERS, maintaining ease of manufacture through a single integrated process

The alternating nanosheet layer structure serves multiple functions simultaneously: it defines the trunk positions, controls branch spacing, determines structural thickness through layer thickness, and enables selective etching through different material compositions. This universal approach allows a single fabrication process to produce reproducible nanotree structures with precise dimensions across large-scale manufacturing

The patent replaces complex mechanical alignment and assembly processes with a self-organizing chemical etching process. The alternating nanosheet layers automatically define the nanotree structure through their inherent layering and etch selectivity, eliminating the need for precise mechanical positioning during fabrication and enabling consistent dimensional reproducibility across mass production