title: From point defects in graphene to two-dimensional amorphous carbon.
abstract: While crystalline two-dimensional materials have become an experimental reality during the past few years, an amorphous 2D material has not been reported before. Here, using electron irradiation we create an sp2-hybridized one-atom-thick flat carbon membrane with a random arrangement of polygons, including four-membered carbon rings. We show how the transformation occurs step by step by nucleation and growth of low-energy multivacancy structures constructed of rotated hexagons and other polygons. Our observations, along with first-principles calculations, provide new insights to the bonding behavior of carbon and dynamics of defects in graphene. The created domains possess a band gap, which may open new possibilities for engineering graphene-based electronic devices.
authors.affiliation: Department of Physics, University of Helsinki, Post Office Box 43, 00014 Helsinki, Finland. jani.kotakoski@iki.fi
authors.forename: J
authors.initials: J
authors.lastname: Kotakoski
authors.forename: A V
authors.initials: AV
authors.lastname: Krasheninnikov
authors.forename: U
authors.initials: U
authors.lastname: Kaiser
authors.forename: J C
authors.initials: JC
authors.lastname: Meyer