High Enhancement, Low Cost, Large Area SERS substrates by ALD Deposited Porous Polymeric Filter Networks

We propose an innovative all ALD approach to achieve super enhancement, ultra-sensitive SERS active substrates which also offers not only high reproducibility, high performance consistency and reliability, but also low cost and scalability for high volume manufacturing. Our key innovations include: 1) Porous polymer filter membranes with uniformly distributed and uniformly sized fine surface feature are used as the SERS substrate matrix material. They have excellent chemical stability, physical strength, and inherent low fluorescence background. Such membrane, having been well developed for water purification and water desalination, are also commercially available at very low cost; 2) Atomic layer deposition (ALD) techniques are used to deposit not only sub-nanometer thin passivation layer on our proposed nanostructures proven effective in the past, and wetting layers onto the polymer filter surface but also directly deposit metallic nanoparticles (Au, Ag). The super conformal coatings due to the self-limiting nature of the ALD process significantly increase surface coverage of metallic nanoparticles on the porous filter membranes, therefore maximize enhancement factor and sensitivity. A super enhancement factor >106 is expected. In addition the capability of large area deposition and the compatibility with high volume batch process or roll-to-roll process will not only make possible large area SERS substrates but also greatly reduce their manufacturing cost.