Single orientation graphene synthesized on iridium thin films grown by molecular beam epitaxy

Abstract

Heteroepitaxial iridium thin films were deposited on (0001) sapphire substrates by means of molecular beam epitaxy, and subsequently, one monolayer of graphene was synthesized by chemical vapor deposition. The influence of the growth parameters on the quality of the Ir films, as well as of graphene, was investigated systematically by means of low energy electron diffraction, x-ray reflectivity, x-ray diffraction, Auger electron spectroscopy, scanning electron microscopy, and atomic force microscopy. Our study reveals (111) oriented iridium films with high crystalline quality and extremely low surface roughness, on which the formation of large-area epitaxial graphene is achieved. The presence of defects, like dislocations, twins, and 30° rotated domains in the iridium films is also discussed. The coverage of graphene was found to be influenced by the presence of 30° rotated domains in the Ir films. Low iridium deposition rates suppress these rotated domains and an almost complete coverage of graphene was obtained. This synthesis route yields inexpensive, air-stable, and large-area graphene with a well-defined orientation, making it accessible to a wider community of researchers for numerous experiments or applications, including those which use destructive analysis techniques or irreversible processes. Moreover, this approach can be used to tune the structural quality of graphene, allowing a systematic study of the influence of defects in various processes like intercalation below graphene.

Exploring Interfaces Through Synchrotron Radiation Characterization Techniques: A Graphene Case

“…[ 85 ] Because surface diffraction has a very high demand on the flatness of the substrate, it is impossible to get the information of twisted azimuth on these rough metal substrates or curved substrates. Currently, tests can only be implemented on specific substrates such as SiC, [ 86 ] Si/SiO 2 , [ 87 ] Ir (111), [ 88 ] Ge (110). [ 89 ] Therefore, other auxiliary methods, such as SR ARPES, are applied to measure the electronic structure of graphene under different stacks, thus reflecting the stack information indirectly.…”

Surface Engineering of Substrates for Chemical Vapor Deposition Growth of Graphene and Applications in Electronic and Spintronic Devices

“…However, because of the weak coupling between Ir and graphene, it might cause the relative lattice rotation between graphene and Ir, thus producing polycrystalline graphene . For preparing single-crystal graphene on Ir surface, a high-quality Ir(111) substrate is a key issue . Under the high temperature, a single-crystal graphene film was synthesized on the Ir(111)/sapphire .…”

“…For preparing single-crystal graphene on Ir surface, a high-quality Ir(111) substrate is a key issue . Under the high temperature, a single-crystal graphene film was synthesized on the Ir(111)/sapphire . Subsequently, the large-scale single-crystal graphene film was successfully synthesized on Ir(111) at a relatively low temperature (LT) of 800 K (Figure d) .…”

Probing Exfoliated Graphene Layers and Their Lithiation with Microfocused X-rays

“…Notable examples are the graphene on SiC 6−12 as well as the graphene on Ir(111) system. 13 In either case, XRD proved to be a sensitive probe to the intercalation of foreign species: hydrogen in graphene on SiC, 14 oxygen in graphene on SiC, 15 and cobalt in graphene on Ir(111). 16 More recently, also epitaxial graphene on Ge(110) 17 as well as chemical vapor deposited graphene on SiO 2 -terminated Si 18 were investigated by XRD.…”

“…These works have been restricted to thin-film systems with a lateral extent of the atomically thin samples reaching the centimeter scale. Notable examples are the graphene on SiC − as well as the graphene on Ir(111) system . In either case, XRD proved to be a sensitive probe to the intercalation of foreign species: hydrogen in graphene on SiC, oxygen in graphene on SiC, and cobalt in graphene on Ir(111) .…”