Small-period DUV plasmonic Al nanohole arrays fabricated by wet colloidal template/substrate and the interface and hole size-dependent E-field enhancement effect.

The fabrication of a uniform small-period Al nanohole array with pronounced deep-ultraviolet (DUV) plasmon is highly valuable in enhancing the intrinsic fluorescence of biochemical molecules for label-free detection. Since metal nanohole arrays have distinct optical transmission properties, it is often questioned whether the maximum electric field (E-field) enhancement effect coincides with the transmission peaks or transmission troughs. We efficiently fabricated uniform DUV plasmonic Al nanohole arrays with small periods by using a wet colloidal template/substrate in a facile and low-cost way. Further, theoretical simulation demonstrates that such an Al nanohole array exhibits interface and hole size-dependent multi-band E-field enhancement effects. We have analyzed the maximum E-field enhancement effect as well as the corresponding exciting wavelength (or ). At the metal-air interface, is close to the transmission peak wavelength when the metal hole diameter is relatively small compared to the period, while approaches the transmission trough wavelength when the hole diameter is relatively large. At the metal- interface, the results are more complicated. The research will provide a reference for the simple synthesis of uniform and small-period Al nanohole arrays and promote the fundamental understanding of the E-field enhancement of the nanohole array. The multi-band E-field enhancement extended to the DUV region will be important for label-free optical detection of multiple biochemical molecules.