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ScienceDaily_2013 01180.txt

#Growing giants: Huge grains of copper promote better graphene growthto technology insiders graphene is certified a big deal. The one-atom thick carbon-based material elicits rhapsodic descriptions as the strongest thinnest material known. It also is light flexible and able to conduct electricity as well as copper. Graphene-based electronics promise advances such as faster internet speeds cheaper solar cells novel sensors space suits spun from graphene yarn and more. Now a research team at the National Institute of Standards and Technology (NIST) in Boulder Colo. may help bring graphene's promise closer to reality. While searching for an ideal growth platform for the material investigators developed a promising new recipe for a graphene substrate: a thin film of copper with massive crystalline grains. The team's findings appear in the journal AIP Advances which is produced by AIP Publishing. The key advance is the grain size of the copper substrate. The large grains are several centimeters in size--lunkers by microelectronics standards --but their relative bulk enables them to survive the high temperatures needed for graphene growth explained NIST researcher Mark Keller. The inability of most copper films to survive this stage of graphene growth has been one problem preventing wafer-scale production of graphene devices Keller said. Thin films are an essential component of many electronic optical and medical technologies but the grains in these films are typically smaller than one micrometer. To fabricate the new copper surface whose grains are about 10000 times larger the researchers came up with a two-step process. First they deposited copper onto a sapphire wafer held slightly above room temperature. Second they added the transformative step of annealing or heat-treating the film at a much higher temperature near the melting point of copper. To demonstrate the viability of their giant-grained film the researchers successfully grew graphene grains 0. 2 millimeters in diameter on the new copper surface. Story Source: The above story is provided based on materials by American Institute of Physics. Note: Materials may be edited for content and length. Journal Reference e

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