Nojoon Myoung, Kyungchul Seo, Seung Joo Lee, Gukhyung Ihm
Graphene has been considered to be a promising material for future electronics due to its extraordinary properties such as high carrier mobility, thermal conductivity and strong break strength. Although the extremely high electrical conductivity makes graphene a candidate for replacing silicon-based electronics, Klein tunneling causes that electrical transport of Dirac fermions is insensitive to electrostatic potentials, resulting a low current on/off ratio of graphene-based field effect transistors. In order to increase the current on/off ratio, vertical graphene heterostructures have been introduced as an alternative device architecture, by using quantum tunneling. Here, in addition to the experimental observations which gave us a large current on/off ratio of graphene/MoS$_{2}$ heterostructures, we present that the current on/off ratio is enhanced by as large as two orders of magnitude compared to the previous report. Moreover, we also report a novel utility of the graphene/MoS$_{2}$ heterostructures as a spin-filter. When a thin MoS$_{2}$ layer sandwiched between two graphene sheets becomes magnetic because of the inversion symmetry breaking, Dirac fermions with different spins feel different heights of a tunnel barrier, resulting spin-dependent tunneling. Our findings will develop the present graphene heterostructures for electronic devices by improving the device performance and by adding the functionality to the existing graphene heterostructures.
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http://arxiv.org/abs/1302.0945
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