Owing to their low dimensionality, two-dimensional semiconductors, such as monolayer molybdenum disulfide, have a range of properties that make them valuable in the development of nanoelectronics. For example, the electronic bandgap of these semiconductors is not an intrinsic physical parameter and can be engineered by manipulating the dielectric environment around the monolayer. Here we show that this dielectric-dependent electronic bandgap can be used to engineer a lateral heterojunction within a homogeneous MoS2 monolayer. We visualize the heterostructure with Kelvin probe force microscopy and examine its influence on electrical transport experimentally and theoretically. We observe a lateral heterojunction with an approximately 90 meV band offset due to the differing degrees of bandgap renormalization of monolayer MoS2 when it is placed on a substrate in which one segment is made from an amorphous fluoropolymer (Cytop) and another segment is made of hexagonal boron nitride. This heterostructure leads to a diode-like electrical transport with a strong asymmetric behaviour.
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We thank M. Asta, J. Yao and S. Kahn for helpful discussions. This work was primarily supported by the Center for Computational Study of Excited State Phenomena in Energy Materials, which is funded by the US Department of Energy, Office of Science, Basic Energy Sciences, Materials Sciences and Engineering Division under Contract No. DE-AC02-05CH11231, as part of the Computational Materials Sciences Program. The device fabrication is supported by the National Science Foundation EFRI Program (EFMA-1542741). This research used resources of the National Energy Research Scientific Computing Center (NERSC), a DOE Office of Science User Facility supported by the Office of Science of the US Department of Energy under Contract No. DE-AC02-05CH11231, and the Extreme Science and Engineering Discovery Environment (XSEDE), which is supported by National Science Foundation grant number ACI-1548562. H.K. was supported by the Deutsche Forschungsgemeinschaft (KL 2961/1-1). C.S.O. acknowledges support from the Singapore National Research Foundation (Clean Energy) PhD Scholarship. R.K. was supported by the JSPS Overseas Research Fellowship Program. S.T. acknowledges support from a NSF DMR 1552220 NSF CAREER award. Growth of hexagonal boron nitride crystals was supported by the Elemental Strategy Initiative conducted by the MEXT, Japan and a Grant-in-Aid for Scientific Research on Innovative Areas ‘Science of Atomic Layers’ from JSPS.
Supplementary Notes 1–4 and Supplementary Figures 1–10