Ultrathin Suspended Nanopores with Surface Plasmon Resonance Fabricated by Combined Colloidal Lithography and Film Transfer

Suspended plasmonic nanopores in ultrathin film layers were fabricated through a simple and widely applicable method combining colloidal lithography and thin film transfer, which allows mass production of short-range ordered nanopore arrays on a large scale. By this combined method, mechanically stable and flexible free-standing nanopore membranes with a thickness down to 15–30 nm were produced. The plasmon resonances of the ultrathin plasmonic nanopores fabricated in AlN/Au/AlN trilayer and single layer Au membranes were tuned to lie in the vis–NIR wavelength range by properly designing their dimensions. The optical responses to the refractive index changes were tested and applied to adlayer sensing. The trilayer nanopore membrane showed a unique property to support water only on one side of the membrane, which was confirmed by the resonance shift and comparison with numerical simulation. Pore size reduction down to 10 nm can be achieved through additional material deposition. The filtering function of s...