Surface Plasmon-Driven Hot Electron Flow Probed with Metal-Semiconductor Nanodiodes

Abstract

A continuous flow of hot electrons that are not at thermal equilibrium with the surrounding metal atoms is generated by the absorption of photons. Here we show that hot electron flow generated on a gold thin film by photon absorption (or internal photoemission) is amplified by localized surface plasmon resonance. This was achieved by direct measurement of photocurrent on a chemically modified gold thin film of metal-semiconductor (TiO(2)) Schottky diodes. The short-circuit photocurrent obtained with low-energy photons is consistent with Fowler's law, confirming the presence of hot electron flows. The morphology of the metal thin film was modified to a connected gold island structure after heating such that it exhibits surface plasmon. Photocurrent and optical measurements on the connected island structures revealed the presence of a localized surface plasmon at 550 ± 20 nm. The results indicate an intrinsic correlation between the hot electron flow generated by internal photoemission and localized surface plasmon resonance.

Harvesting the loss: surface plasmon-based hot electron photodetection

“…(1) predicts an increasing quantum yield at higher photon energy. Many recently demonstrated hot electron photodetectors based on Schottky barriers have been shown to follow this model [44,48,66]. Compared to electron-hole generation and separation in a semiconductor, the internal photoemission over a bulk metal/semiconductor Schottky junction is a very inefficient process.…”

Molecular interfaces for plasmonic hot electron photovoltaics

“…18,[23][24][25] To this end, metal-semiconductor (MS) Schottky junctions have been employed, 11,12,26 that take advantage of the built-in field in the vicinity of the metal nanostructure to separate the photogenerated carriers. The use of metalinsulator-metal architectures was also successfully employed for hot-electron photodetection.…”

Plasmon-enhanced photocurrent generation and water oxidation from visible to near-infrared wavelengths

“…[15][16][17][18][19] Therefore, it is understood that metallic nanostructures act as photoelectric conversion systems that enable the effective utilization of photons, having a role similar to that of chlorophyll in photosynthesis. [20][21][22][23] Although many photoelectric conversion systems using LSPR have been previously reported, the wavelengths at which photoelectric conversion occurs did not extend beyond 700 nm, [24][25][26][27][28][29][30][31] creating a need to explore photoelectric conversion at infrared wavelengths past 800 nm.…”