Plasmonic Hot Electron Induced Photocurrent Response at MoS2-Metal Junctions.

We investigate the wavelength- and polarization-dependence of photocurrent signals generated at few-layer MoS2-metal junctions through spatially resolved photocurrent measurements. When incident photon energy is above the direct bandgap of few-layer MoS2, the maximum photocurrent response occurs for the light polarization direction parallel to the metal electrode edge, which can be attributed to photovoltaic effects. In contrast, if incident photon energy is below the direct bandgap of MoS2, the photocurrent response is maximized when the incident light is polarized in the direction perpendicular to the electrode edge, indicating different photocurrent generation mechanisms. Further studies show that this polarized photocurrent response can be interpreted in terms of the polarized absorption of light by the plasmonic metal electrode, its conversion into hot electron-hole pairs, and subsequent injection into MoS2. These fundamental studies shed light on the knowledge of photocurrent generation mechanisms in metal-semiconductor junctions, opening the door for engineering future two-dimensional materials based optoelectronics through surface plasmon resonances.