Controlling the number of layers in graphene using the growth pressure.

Monolayer graphene is commonly grown on Cu substrates due to the self-limiting nature of graphene synthesis by chemical vapor deposition (CVD). Consequently, the growth of multilayer graphene by CVD has proven to be relatively difficult. This study demonstrates that the number of layers in graphene synthesized on a copper substrate can be precisely set by controlling the partial pressure of hydrogen gas used in the CVD process.

Adhesion and Self-Healing between Monolayer Molybdenum Disulfide and Silicon Oxide.

The adhesion interactions of two-dimensional (2D) materials are of importance in developing flexible electronic devices due to relatively large surface forces. Here, we investigated the adhesion properties of large-area monolayer MoS grown on silicon oxide by using chemical vapor deposition. Fracture mechanics concepts using double cantilever beam configuration were used to characterize the adhesion interaction between MoS and silicon oxide.

Growth of Monolayer Graphene on Nanoscale Copper-Nickel Alloy Thin Films.

Growth of high quality and monolayer graphene on copper thin films on silicon wafers is a promising approach to massive and direct graphene device fabrication in spite of the presence of potential dewetting issues in the copper film during graphene growth. Current work demonstrates roles of a nickel adhesion coupled with the copper film resulting in mitigation of dewetting problem as well as uniform monolayer graphene growth over 97 % coverage on films. The feasibility of monolayer graphene growth on Cu-Ni alloy films as thin as 150 nm in total is also demonstrated.

Large-Area Dry Transfer of Single-Crystalline Epitaxial Bismuth Thin Films.

We report the first direct dry transfer of a single-crystalline thin film grown by molecular beam epitaxy. A double cantilever beam fracture technique was used to transfer epitaxial bismuth thin films grown on silicon (111) to silicon strips coated with epoxy. The transferred bismuth films retained electrical, optical, and structural properties comparable to the as-grown epitaxial films.

Cracking of Polycrystalline Graphene on Copper under Tension.

Roll-to-roll manufacturing of graphene is attractive because of its compatibility with flexible substrates and its promise of high-speed production. Several prototype roll-to-roll systems have been demonstrated, which produce large-scale graphene on polymer films for transparent conducting film applications.1-4 In spite of such progress, the quality of graphene may be influenced by the tensile forces that are applied during roll-to-roll transfer.

Selective mechanical transfer of graphene from seed copper foil using rate effects.

A very fast, dry transfer process based on mechanical delamination successfully effected the transfer of large-area, CVD grown graphene on copper foil to silicon. This has been achieved by bonding silicon backing layers to both sides of the graphene-coated copper foil with epoxy and applying a suitably high separation rate to the backing layers. At the highest separation rate considered (254.

Ultra long-range interactions between large area graphene and silicon.

The wet-transfer of graphene grown by chemical vapor deposition (CVD) has been the standard procedure for transferring graphene to any substrate. However, the nature of the interactions between large area graphene and target substrates is unknown. Here, we report on measurements of the traction-separation relations, which represent the strength and range of adhesive interactions, and the adhesion energy between wet-transferred, CVD grown graphene and the native oxide surface of silicon substrates.