Unraveling the Water Impermeability Discrepancy in CVD‐Grown Graphene

Abstract

Graphene has recently attracted particular interest as a flexible barrier film preventing permeation of gases and moistures. However, it has been proved to be exceptionally challenging to develop large-scale graphene films with little oxygen and moisture permeation suitable for industrial uses, mainly due to the presence of nanometer-sized defects of obscure origins. Here, the origins of water permeable routes on graphene-coated Cu foils are investigated by observing the micrometer-sized rusts in the underlying Cu substrates, and a site-selective passivation method of the nanometer-sized routes is devised. It is revealed that nanometer-sized holes or cracks are primarily concentrated on graphene wrinkles rather than on other structural imperfections, resulting in severe degradation of its water impermeability. They are found to be predominantly induced by the delamination of graphene bound to Cu as a release of thermal stress during the cooling stage after graphene growth, especially at the intersection of the Cu step edges and wrinkles owing to their higher adhesion energy. Furthermore, the investigated routes are site-selectively passivated by an electron-beam-induced amorphous carbon layer, thus a substantial improvement in water impermeability is achieved. This approach is likely to be extended for offering novel barrier properties in flexible films based on graphene and on other atomic crystals.

The Wet‐Oxidation of a Cu(111) Foil Coated by Single Crystal Graphene

“…However to date, atomic defects have always been present in the CVD grown graphene samples, both inside the graphene islands (also referred to as "domains"), and at the grain boundaries (GBs), formed when graphene islands with different lattice orientations join during growth [12] and/or at the graphene wrinkles/folds [13] formed due to the mismatch of thermal expansion coefficients between graphene and the metal substrate-in short, due to interfacial stress during contraction of the metal foil substrate upon cooling from the growth temperature to room temperature. [14,15] These regions containing…”

Recent Developments in Controlled Vapor‐Phase Growth of 2D Group 6 Transition Metal Dichalcogenides

“…The excellent properties of two-dimensional (2D) nanosheet materials have attracted a great deal of interest worldwide due to the popularity of graphene in various applications. [1][2][3][4][5][6][7][8] Over the past decade, graphene has been at the forefront of nanomaterials research; however, graphene is not suitable for widespread use in novel 2D semiconductor applications as it lacks a sizable natural energy gap, which makes achieving low-power dissipation in the "off" state difficult. Graphene must be extensively modified (through strain, alloying, or other band gap engineering methods) [9][10][11][12] to create the required energy gap.…”

“…[13] In particular, 2D group 6 transition metal (TM) dichalcogenides (TMDs), such as (Mo, W)(S, Se, Te) 2 , have opened new avenues for engineering future electronic and optoelectronic devices. [14][15][16] For instance, MoS 2 -based field-effect transistors (FETs) exhibit excellent electrical performance with high on-off current ratios (~10 8 at room temperature (RT)) [14] and may be used in future electrical circuits that require low stand-by power. Strong emission and large exciton binding energy originating from the direct bandgap structure of monolayer MoS 2 flakes can be exploited for superior optoelectronic applications.…”

Teknologi Material Maju : Prinsip Dasar dan Aspek Rekayasa

“…Quantum dots adalah sering dianggap sebagai atom buatan, di mana efek kurungan kuantum secara signifikan mengganggu sifat elektronik massal yang umum dari materi (6; 168-170). Salah satu metode pertumbuhan kuantum titik melibatkan penyetoran satu materi pada yang lain dengan ketidakcocokan kisi besar (171)(172)(173).…”