Figure 1: Device overview and band diagrams.
From: Distinguishing between plasmon-induced and photoexcited carriers in a device geometry
Schematic of hot-carrier generation and collection over a Schottky (a) or an Ohmic barrier (b). Plasmonic hot-carrier generation from surface plasmons is localized to areas of large field enhancements, while hot carriers generated from interband absorption can occur throughout the bulk material, limited instead by absorption depth. Band diagram schematics of (c) a Au-TiO2 Schottky device and (d) a Au-Ti-TiO2 Ohmic device. Carrier generation by direct photoexcitation results from the excitation of d-band electrons, 2.3 eV below the Fermi level, into the conduction band. Their low energy prevents them from crossing the Schottky barrier (∼1 eV). Ohmic devices have no effective barrier and allows for collection of carriers created by this process. The wide bandgap of the semiconductor allows preferential collection of electrons. (e) Representative scanning-electron microscope (SEM) image of a fabricated nanostructure comprised of a contact pad and a nanowire array. Current-voltage (I–V) curves of Schottky (f) and Ohmic devices (g). Red curves are the averages and all measured I–V curves fall within the grey bounded regions.
