Publications List
  • 09-06-2017

    How Graphene Islands Are Unidirectionally Aligned on the Ge(110) Surface

    The unidirectional alignment of graphene islands is essential to the synthesis of wafer-scale single-crystal graphene on Ge (110) surface, but the underlying mechanism is not well-understood. Here we report that the necessary co-alignment of the nucleating graphene islands on Ge (110) surface caused by the presence of step pattern; we show that on the preannealed Ge (110) textureless surface the graphene islands appear non-preferentially orientated, while on the Ge(110) surfaces with natural step pattern, all graphene islands emerge co-aligned. First-principles calculations and theoretical analysis reveal this different alignment behaviors originate from the strong chemical binding formed between the graphene island edges and the atomic ...[ Learn more ]

  • 09-06-2017

    High-Tc superconductivity in ultrathin Bi2Sr2CaCu2O8+x down to half-unit-cell thickness by protection with graphene

    High-T-c superconductors confined to two dimension exhibit novel physical phenomena, such as superconductor-insulator transition. In the Bi2Sr2CaCu2O8+x (Bi2212) model system, despite extensive studies, it is difficult to determine the intrinsic superconducting properties at the thinness limit. Here, we report a method to fabricate high quality single-crystal Bi2212 films down to half-unit-cell thickness in the form of graphene/Bi2212 van der Waals heterostructure, in which sharp superconducting transitions are observed. The heterostructure also exhibits a nonlinear current-voltage characteristic due to the Dirac nature of the graphene band structure.[ Learn more ]

  • 09-06-2017

    Direct observation of titanium-centered octahedra in titanium-antimony-tellurium phase-change material

    Phase-change memory based on Ti0.4Sb2Te3 material has one order of magnitude faster set speed and as low as one-fifth of the reset energy compared with the conventional Ge2Sb2Te5 based device. However, the phase-transition mechanism of the Ti0.4Sb2Te3 material remains inconclusive due to the lack of direct experimental evidence. Here we report direct atom-by-atom chemical identification of titanium-centered octahedra in crystalline Ti0.4Sb2Te3 material with a state-of-the-art atomic mapping technology. Further, by using soft X-ray absorption spectroscopy and density function theory simulations, we identify in amorphous Ti0.4Sb2Te3 the titanium atoms preferably maintain the octahedral configuration. Our work may pave the way to more thoro...[ Learn more ]

  • 09-06-2017

    Fast growth of inch-sized single-crystalline graphene from a controlled single nucleus on Cu-Ni alloys

    Wafer-scale single-crystalline graphene monolayers are highly sought after as an ideal platform for electronic and other applications (1-3). At present, state-of-the-art growth methods based on chemical vapour deposition allow the synthesis of one-centimeter-sized single-crystalline graphene domains similar to 12 h, by suppressing nucleation events on the growth substrate (4). Here we demonstrate an efficient strategy for achieving large-area single-crystalline graphene by letting a single nucleus evolve in a monolayer at a fast rate. By locally feeding carbon precursors to a desired position of a substrate composed of an optimized Cu-Ni alloy, we synthesized an similar to 1.5-inch-large graphene monolayer in 2.5 h. Localized feeding ind...[ Learn more ]

  • 09-06-2017

    Information Functional Materials State Key Laboratory of the fifth session of the four academic committee was success...