Preventing Corrosion of Aluminum Metal with Nanometer-Thick Films of Al₂O₃ Capped with TiO₂ for Ultraviolet Plasmonics

Extending plasmonics into the ultraviolet range imposes use of aluminum to achieve best optical performance. However, water corrosion is a major limiting issue for UV plasmonics, as this phenomenon occurs significantly faster in presence light, even at low laser powers few microwatts. Here we assess performance nanometer-thick layers various metal oxides deposited by atomic layer deposition (ALD) and plasma-enhanced chemical vapor (PECVD) on top nanoapertures protect against photocorrosion. The combination 5 nm Al2O3 covered TiO2 capping provides resistance performance, while single 10 SiO2 or HfO2 good alternative. We also report influence wavelength, operation mode pH solution. Properly choosing these conditions extends which nanostructures can be used. As application, demonstrate label-free detection streptavidin proteins with improved signal noise ratio. Our approach beneficial promote long-term stability nanostructures. Finding appropriate nanoscale protection key enable development plasmonic applications chemistry biology.