A research team at the Daejeon-based Institute for Basic Science has succeeded in growing single-crystal graphene films that have no wrinkles, folds or adlayers, paving the way for technological advancement in a wide range of fields and industries, including semiconductors, displays and solar cell products.

Led by professor Rod Ruoff, the research, titled “Single Crystal, Large-area, Fold-free Monolayer Graphene,” has been published in the leading science journal Nature.

Graphene is a single layer of carbon atoms, tightly bound in a hexagonal honeycomb lattice nanostructure. It is 200 times stronger than steel, while its density is similar to that of carbon fiber. Graphene is one of the most conductive materials for electricity and heat, making it perfect for electronics and many other industries.

The team had previously reported that single-crystal and adlayer-free films of graphene could be grown by using methane at temperatures less than 1320 Kelvin degrees on copper foils.

However, the team was unable to get rid of folds formed when the graphene was cooled from the growth temperature, which resulted in an undesirable reduction in the performance.

The latest research, however, presented a method to achieve the most uniform graphene.

Professor Ruoff and his research team conducted a series of experiments to grow single-crystal and single-layer graphene films on homemade Cu-nickel foils under different temperatures.

The team there found that folds are formed at or above 1030 K during the cooling process. The team decided to grow graphene on Cu-Ni foils at several different temperatures around 1030 K, which led to a discovery that large-area, fold-free and adlayer-free single-crystal graphene films could be grown in a temperature range between 1000 and 1030 K.

According to the research team, the graphene without folds can carry electric charges faster than currently used materials, seven times faster than silicon and three times faster than existing graphene.

Director Ruoff said the research team will continue to conduct experiments involving the team’s graphene.