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arXiv · 1808.02119

Asymmetric Schottky Contacts in Bilayer MoS2 Field Effect Transistors

Antonio Di Bartolomeo·Alessandro Grillo·Francesca Urban·Laura Iemmo·Filippo Giubileo·Giuseppe Luongo·Giampiero Amato·Luca Croin·Linfeng Sun·Shi-Jun Liang·Lay Kee Ang
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Abstract

We discuss the high-bias electrical characteristics of back-gated field-effect transistors with CVD-synthesized bilayer MoS2 channel and Ti Schottky contacts. We find that oxidized Ti contacts on MoS2 form rectifying junctions with ~0.3 to 0.5 eV Schottky barrier height. To explain the rectifying output characteristics of the transistors, we propose a model based on two slightly asymmetric back-to-back Schottky barriers, where the highest current arises from image force barrier lowering at the electrically forced junction, while the reverse current is due to Schottky-barrier limited injection at the grounded junction. The device achieves a photo responsivity greater than 2.5 AW-1 under 5 mWcm-2 white-LED light. By comparing two- and four-probe measurements, we demonstrate that the hysteresis and persistent photoconductivity exhibited by the transistor are peculiarities of the MoS2 channel rather than effects of the Ti/MoS2 interface.

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Antonio Di Bartolomeo, Alessandro Grillo, Francesca Urban, Laura Iemmo, Filippo Giubileo, Giuseppe Luongo, Giampiero Amato, Luca Croin, Linfeng Sun, Shi-Jun Liang, Lay Kee Ang. 2018-08-06. Asymmetric Schottky Contacts in Bilayer MoS2 Field Effect Transistors. https://doi.org/10.1002/adfm.201800657

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