Large and Tunable Photothermoelectric
Effect in Single-Layer
MoS<sub>2</sub>
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Abstract
We study the photoresponse of single-layer MoS<sub>2</sub> field-effect
transistors by scanning photocurrent microscopy. We find that, unlike
in many other semiconductors, the photocurrent generation in single-layer
MoS<sub>2</sub> is dominated by the photothermoelectric effect and
not by the separation of photoexcited electron–hole pairs across
the Schottky barriers at the MoS<sub>2</sub>/electrode interfaces.
We observe a large value for the Seebeck coefficient for single-layer
MoS<sub>2</sub> that by an external electric field can be tuned between
−4 × 10<sup>2</sup> and −1 × 10<sup>5</sup> μV K<sup>–1</sup>. This large and tunable Seebeck coefficient
of the single-layer MoS<sub>2</sub> paves the way to new applications
of this material such as on-chip thermopower generation and waste
thermal energy harvesting