Large and Tunable Photothermoelectric Effect in Single-Layer MoS2

Abstract

We study the photoresponse of single-layer MoS₂ field-effect transistors by scanning photocurrent microscopy. We find that, unlike in many other semiconductors, the photocurrent generation in single-layer MoS₂ is dominated by the photothermoelectric effect and not by the separation of photoexcited electron–hole pairs across the Schottky barriers at the MoS₂/electrode interfaces. We observe a large value for the Seebeck coefficient for single-layer MoS₂ that by an external electric field can be tuned between −4 × 10² and −1 × 10⁵ μV K^–1. This large and tunable Seebeck coefficient of the single-layer MoS₂ paves the way to new applications of this material such as on-chip thermopower generation and waste thermal energy harvesting.