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ion Disappearing Nano-Particles

Bryan D. Huey, University of Connecticut, DMR 0909091Outcome: Scientists at the University of Connecticut have directly observed silver nanoparticles ‘disappearing’ from a glass surface upon illumination.Impact: High fidelity photomasks are crucial to the continued advancement of semiconductor devices. In this silver nanoparticle-chalcogenide glass system, illumination causes the silver from the particles to completely diffuse into the film, with a corresponding change in color and transparency. This ceramic system is inherently more robust than traditional organic mask coatings.

Explanation:Upon exposure, Ag ions from Ag nanoparticles begins to diffuse into the underlying chalcogenide film due to optically generated charge gradients. Over the first 4 minutes this causes moderate faceting and roughening of the particles, but in the next 1 minute (3 consecutive AFM images) a completely smooth surface emerges.

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Nanoparticles in a 20 um by 1.25 µm region completely disappearing due to diffusion into the underlying glass film, excited by patterned illumination. (courtesy B. Huey, University of Connecticut)

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