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We investigate the transport properties of the van der Waals (vdW) junction between a layered superconductor $\mathrm{Nb}{\mathrm{Se}}_{2}$ and a graphene. A superconductor/graphene (S/G) vdW junction is fabricated by dry transferring a freshly exfoliated $\mathrm{Nb}{\mathrm{Se}}_{2}$ flake onto a graphene surface. This vdW junction provides a transparent superconductor/graphene contact as well as metal-induced doping in the graphene layer underneath, thereby facilitating vdW coupling-induced superconductivity in the graphene under the $\mathrm{Nb}{\mathrm{Se}}_{2}$ layer. The $\mathrm{Nb}{\mathrm{Se}}_{2}/\text{superconducting}$ graphene (Sc-graphene)/graphene structure causes the differential resistance of the vdW junction to exhibit zero-bias dip and multiple peaks at larger bias. All of these features are explained by the coexistence of two different S/G interfaces in the device; these are lateral Sc-graphene/graphene and vertical $\mathrm{Nb}{\mathrm{Se}}_{2}/\mathrm{Sc}$-graphene. A proximity-induced superconducting gap ${\mathrm{\ensuremath{\Delta}}}_{\mathrm{i}}$ in the Sc-graphene is detected by Andreev reflection at the lateral Sc-graphene/graphene junction and the determined ${\mathrm{\ensuremath{\Delta}}}_{\mathrm{i}}=0.05\ensuremath{-}0.06\phantom{\rule{0.16em}{0ex}}\mathrm{meV}$.

Atomically-thin black phosphorus (BP) is an emerging two dimensional (2D) material exhibiting bright photoluminescence in the near infrared. Coupling its radiation to photonic nanostructures will be an important step toward the realization of 2D material based nanophotonic devices that operate efficiently in the near infrared, which includes the technologically important optical telecommunication wavelength bands. In this letter, we demonstrate the optical coupling between atomically-thin BP and a 2D photonic crystal nanocavity. We employed a home-build dry transfer apparatus for placing a thin BP flake on the surface of the nanocavity. Their optical coupling was analyzed through measuring cavity mode emission under optical carrier injection at room temperature., 13 pages, 4 figures. This article has already been published in Applied Physics Letters

We demonstrate a vertical field-effect transistor based on a graphene/MoSe2 van der Waals (vdW) heterostructure. The vdW interface between the graphene and MoSe2 exhibits a Schottky barrier with an ideality factor of around 1.3, suggesting a high-quality interface. Owing to the low density of states in graphene, the position of the Fermi level in the graphene can be strongly modulated by an external electric field. Therefore, the Schottky barrier height at the graphene/MoSe2 vdW interface is also modulated. We demonstrate a large current ON-OFF ratio of 10^5. These results point to the potential high performance of the graphene/MoSe2 vdW heterostructure for electronics applications., 17 pages, 4 figures

We demonstrated exfoliated-graphene/transition metal dichalcogenide (TMD)/metal vertical field-effect transistor (vFET). The van der Waals junction between graphene and TMD exhibit Schottky barrier. Owing to the low density of state of graphene, the position of graphene's Fermi level can be modulated by the external electric field, thus enable us electric field modulation of Schottky barrier height at graphene/TMD interface. Based on this mechanism, a vertical transport in the heterostructure exhibits large current modulation of 105, and at the same time the heterostructure reveal operation current density of 104 A/cm2. These results reveal potential high performance of vFET for flexible electronics applications.

We investigate the micromechanical exfoliation and van der Waals (vdW) assembly of ferromagnetic layered dichalcogenide Fe0.25TaS2. The vdW interlayer coupling at the Fe-intercalated plane of Fe0.25TaS2 allows exfoliation of flakes. A vdW junction between the cleaved crystal surfaces is constructed by dry transfer method. We observe tunnel magnetoresistance in the resulting junction under an external magnetic field applied perpendicular to the plane, demonstrating spin-polarized tunneling between the ferromagnetic layered material through the vdW junction., Comment: 16 pages, 4 figures

Detail transport properties of graphene/MoS2/metal vertical heterostructure have been investigated. The van der Waals interface between the graphene and MoS2 exhibits Schottky barrier. The application of gate voltage to the graphene layer enables us to modulate the Schottky barrier height; thus gives rise to the control of the current flow across the interface. By analyzing the temperature dependence of the conductance, the modulation of Schottky barrier height {\Delta}{\phi} has been directly determined. We observed significant MoS2 layer number dependence of {\Delta}{\phi}. Moreover, we demonstrate that the device which shows larger {\Delta}{\phi} exhibits larger current modulation; this is consistent with the fact that the transport of these devices is dominated by graphene/MoS2 Schottky barrier., Comment: Proceeding for 2014 International Conference on Solid State Devices and Materials (SSDM2014)