Large and tunable photothermoelectric effect in single-layer MoS2

Area of Science:

• Condensed Matter Physics
• Materials Science
• Nanotechnology

Background:

• Single-layer molybdenum disulfide (MoS2) is a promising 2D material for electronic and optoelectronic applications.
• Understanding photocurrent generation mechanisms is crucial for optimizing MoS2-based devices.

Purpose of the Study:

• To investigate the photoresponse mechanism in single-layer MoS2 field-effect transistors.
• To quantify the contribution of different photocurrent generation pathways.

Main Methods:

• Scanning photocurrent microscopy was employed to study single-layer MoS2 field-effect transistors.
• The Seebeck coefficient was measured and tuned using an external electric field.

Main Results:

• Photocurrent generation in single-layer MoS2 is dominated by the photothermoelectric effect, not charge separation across Schottky barriers.
• A large Seebeck coefficient, tunable from -4 × 10^2 to -1 × 10^5 μV K⁻¹, was observed.

Conclusions:

• The photothermoelectric effect is the primary photocurrent mechanism in single-layer MoS2.
• The tunable Seebeck coefficient opens avenues for on-chip thermopower generation and waste heat energy harvesting using MoS2.