Large and Tunable Photothermoelectric Effect in Single-Layer MoS2

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