Manipulation of hot electron flow on plasmonic nanodiodes fabricated by nanosphere lithography

Abstract

The energy conversion to generate hot electrons through the excitation of localized surface plasmon resonance (LSPR) in nanostructured plasmonic metal is an emerging strategy in photovoltaics and photocatalytic devices. Important factors for surface plasmon and hot electron generation are the size, shape, and materials of plasmonic metal nanostructures, which affect LSPR excitation, absorbance, and hot electron collection. Here, we fabricated the ordered structure of metal-semiconductor plasmonic nanodiodes using nanosphere lithography and reactive ion etching. Two types of plasmonic nanostructures, the net-shaped structure and the hole-shaped structure, were fabricated on Au/TiO2 Schottky diodes. We show that hot electron flow can be manipulated by changing the size and shape of plasmonic nanostructures on the Schottky diode. We show that the short-circuit photocurrent changes and the incident photon-to-electron conversion efficiency (IPCE) results exhibit the peak shift depending on the structures. These phenomena are explicitly observed with finite difference time domain (FDTD) simulations. The capability of tuning the morphology of plasmonic nanostructure on the Schottky diode can give rise to new possibilities in controlling hot electron generation and developing novel hot-electron–based energy conversion devices.