Accepted for publication in 2D Materials.
WSe2 homojunctions and quantum dots created by patterned hydrogenation of epitaxial graphene substrates
Yi Pan1,2, Stefan Fölsch1, Yu-Chuan Lin3, Bhakti Jariwala3, Joshua A. Robinson3, Yifan Nie4, Kyeongjae Cho4, and Randall M. Feenstra5
1 Paul-Drude-Institut für Festkörperelektronik, Hausvogteiplatz 5-7, Leibniz-Institut im Forschungsverbund Berlin e. V., 10117 Berlin, Germany
2Center for Spintronics and Quantum Systems, State Key Laboratory for Mechanical Behavior of Materials, Xi’an Jiaotong University, Xi’an 710049, China
3Dept. Materials Science and Engineering, and Center for 2-Dimensional and Layered Materials, The Pennsylvania State University, University Park, PA 16802, USA
4Dept. Materials Science and Engineering, The University of Texas at Dallas, Dallas, TX 75080, USA
5Department of Physics, Carnegie Mellon University, Pittsburgh, PA 15213, USA
Abstract
Scanning tunneling microscopy at 5 K is used to study WSe2 layers grown on epitaxial graphene which is formed on Si-terminated SiC(0001). Specifically, a partial hydrogenation process is applied to intercalate hydrogen at the SiC-graphene interface, yielding areas of quasi-freestanding bilayer graphene coexisting with bare monolayer graphene. We find that an abrupt and structurally perfect homojunction (band-edge offset ~0.25 eV) is formed when WSe2 overgrows a lateral junction between adjacent monolayer and quasi-freestanding bilayer areas in the graphene. The band structure modulation in the WSe2 overlayer arises from the varying work function (electrostatic potential) of the graphene beneath. Scanning tunneling spectroscopy measurements reveal that this effect can be also utilized to create WSe2 quantum dots that confine either valence or conduction band states, in agreement with first-principles band structure calculations.
Click here for preprint of paper, in pdf format.
Return to Home Page of Feenstra group