Photodetection in p-n junctions formed by electrolyte-gated transistors of two-dimensional crystals

Abstract

Transition metal dichalcogenide (TMDC) monolayers have attracted much attention due to their strong light absorption and excellent electronic properties. These advantages make this type of two-dimensional crystal a promising one for optoelectronic device applications. In the case of photoelectric conversion devices such as photodetectors and photovoltaic cells, p-n junctions are one of the most important devices. Here, we demonstrate photodetection with WSe2 monolayer films. We prepare the electrolyte-gated ambipolar transistors and electrostatic p-n junctions are formed by the electrolyte-gating technique at 270 K. These p-n junctions are cooled down to fix the ion motion (and p-n junctions) and we observed the reasonable photocurrent spectra without the external bias, indicating the formation of p-n junctions. Very interestingly, two-terminal devices exhibit higher photoresponsivity than that of three-terminal ones, suggesting the formation of highly balanced anion and cation layers. The maximum photoresponsivity reaches 5 mA/W in resonance with the first excitonic peak. Our technique provides important evidence for optoelectronics in atomically thin crystals.

Accepted in Applied Physics Letters (2016)

References in corpus (8)

• Observation of giant bandgap renormalization and excitonic effects in a monolayer transition metal dichalcogenide semiconductor
• Broadband Linear-Dichroic Photodetector in a Black Phosphorus Vertical p-n Junction
• Quantitative Determination of the Band-Gap of WS2 with Ambipolar Ionic Liquid-Gated Transistors
• High Mobility WSe2 p- and n-Type Field Effect Transistors Contacted by Highly Doped Graphene for Low-Resistance Contacts
• Probing excitonic states in ultraclean suspended two-dimensional semiconductors by photocurrent spectroscopy
• Generation and Electric Control of Spin-Coupled Valley Current in WSe2
• Origin of photoresponse in black phosphorus photo-transistors
• Charge transport in ion-gated mono-, bi-, and trilayer MoS2 field effect transistors