Chalcogenide Photonic Crystals Fabricated by Soft Imprint-Assisted Photodoping of Silver

This work presents a low-cost, large-scale nanofabrication approach that combines imprint lithography and silver doping (IL-SD) to pattern chalcogenide glass (ChG) films for realizing IR devices. The IL-SD method involves controled photodoping of silver (Ag) atoms into ChG films and selective removing of undoped ChG. For photodoping of Ag, an Ag-coated elastomer stamp is brought in contact with the ChG film and exposed to ultraviolet light, and subsequently, the Ag atoms are photo-dissolved into the ChG film following the nanopatterns on the elastomer stamp. Due to the high wet-etching selectivity of the undoped ChG to Ag-doped one, the ChG film can be precisely patterned with a spatial resolution on the order of a few tens of nanometers. Also, by controling the lateral diffusion of Ag atoms during ultraviolet exposure, it is possible to adjust the size of the final patterns formed in the ChG film. As an application demonstration of the IL-SD process, the As₂ S₃ -based near-infrared photonic crystals (PhCs) in the wavelength range and flexible midinfrared PhCs are formed, and their optical resonances are investigated. The IL-SD process enables the low-cost fabrication of ChG nanostructures on different substrate materials and gives a great promise to realize various IR devices.