Engineering on-chip nanoporous gold material libraries via precision photothermal treatment

• Published in: Nanoscale Vol. 8; no. 2; p. 785
• Main Authors: Chapman, Christopher A R, Wang, Ling, Biener, Juergen, Seker, Erkin, Biener, Monika M, Matthews, Manyalibo J
• Format: Journal Article
• Language: English
• Published: England 14-01-2016
• Subjects: Alloys; Biosensing Techniques; Computer Simulation; Diffusion; Finite Element Analysis; Glass; Gold - chemistry; Hot Temperature; Lasers; Materials Testing; Metal Nanoparticles - chemistry; Microscopy, Electron, Scanning - methods; Nanostructures - chemistry; Nitrogen - chemistry; Photochemistry - methods; Porosity; Silicon - chemistry; Silver - chemistry
• ISSN: 2040-3372
• DOI: 10.1039/c5nr04580k

Libraries of nanostructured materials on a single chip are a promising platform for high throughput and combinatorial studies of structure-property relationships in the fields of physics and biology. Nanoporous gold (np-Au), produced by an alloy corrosion process, is a nanostructured material specifically suited for such studies because of its self-similar thermally induced coarsening behavior. However, traditional heat application techniques for the modification of np-Au are bulk processes that cannot be used to generate a library of different pore sizes on a single chip. Here, laser micro-processing offers an attractive solution to this problem by providing a means to apply energy with high spatial and temporal resolution. In the present study we use finite element multiphysics simulations to predict the effects of laser mode (continuous-wave vs. pulsed) and thermal conductivity of the supporting substrate on the local np-Au film temperatures during photothermal annealing. Based on these results we discuss the mechanisms by which the np-Au network is coarsened. Thermal transport simulations predict that continuous-wave mode laser irradiation of np-Au thin films on a silicon substrate supports the widest range of morphologies that can be created through photothermal annealing of np-Au. Using the guidance provided by simulations, we successfully fabricate an on-chip material library consisting of 81 np-Au samples of 9 different morphologies for use in the parallel study of structure-property relationships.