Plasmonic Hot Electron Induced Photocurrent Response at MoS2-Metal Junctions

Area of Science:

• Materials Science
• Condensed Matter Physics
• Nanotechnology

Background:

• Few-layer molybdenum disulfide (MoS2) is a prominent two-dimensional material with unique electronic and optical properties.
• Metal-semiconductor junctions are fundamental building blocks in various optoelectronic devices.
• Understanding photocurrent generation mechanisms is crucial for advancing 2D material-based electronics.

Purpose of the Study:

• To investigate the wavelength- and polarization-dependence of photocurrent in few-layer MoS2-metal junctions.
• To elucidate the underlying mechanisms responsible for observed photocurrent responses.
• To explore the role of surface plasmon resonances in photocurrent generation.

Main Methods:

• Spatially resolved photocurrent measurements were employed.
• Experiments were conducted using varying incident light wavelengths and polarizations.
• Analysis focused on photocurrent signal dependence on light polarization relative to metal electrode edges.

Main Results:

• Above the direct bandgap of MoS2, photocurrent maximized with light polarization parallel to the metal electrode edge, indicating photovoltaic effects.
• Below the bandgap, photocurrent maximized with light polarization perpendicular to the electrode edge, suggesting different generation mechanisms.
• Polarized photocurrent response was linked to polarized light absorption by plasmonic metal electrodes and subsequent hot electron-hole pair injection.

Conclusions:

• Photocurrent generation in MoS2-metal junctions exhibits distinct wavelength and polarization dependencies.
• Surface plasmon resonances in metal electrodes significantly influence photocurrent generation, especially below the bandgap.
• These findings provide insights for engineering 2D material optoelectronics utilizing plasmonic effects.