The Backside of Graphene: Manipulating Adsorption by Intercalation

Abstract

The ease by which graphene is affected through contact with other materials is one of its unique features and defines an integral part of its potential for applications. Here, it will be demonstrated that intercalation, the insertion of atomic layers in between the backside of graphene and the supporting substrate, is an efficient tool to change its interaction with the environment on the frontside. By partial intercalation of graphene on Ir(111) with Eu or Cs we induce strongly n-doped graphene patches through the contact with these intercalants. They coexist with nonintercalated, slightly p-doped graphene patches. We employ these backside doping patterns to directly visualize doping induced binding energy differences of ionic adsorbates to graphene through low-temperature scanning tunneling microscopy. Density functional theory confirms these binding energy differences and shows that they are related to the graphene doping level.

Growth morphology and properties of metals on graphene

“…Huang et al [210] found that the rare earth Ce was unusual, in that it intercalated at 300 K, in contrast to 6 other elements studied, Pt, Pd, Ni, Co, Au, and In, which all required heating to 500-800 K, on G1/Ru(0 0 1). It should be noted that by contrast, Schumacher et al found that the rare earth Eu intercalates under G1/Ir(1 1 1) only at elevated temperatures [201].…”

“…While experiments on exfoliated graphene of various thicknesses from single to multilayers have shown that the island density can depend dramatically on the carbon layer thickness for Cs [37] and for Au [16,17], recent experiments also show that metal intercalation [35,185,[199][200][201] provides a way to effectively modify the properties of graphene and tune the adatom bonding. It has been shown that adsorption of metal atoms can be manipulated by the insertion of metallic layers between graphene and the supporting substrate [201].…”

“…It has been shown that adsorption of metal atoms can be manipulated by the insertion of metallic layers between graphene and the supporting substrate [201]. By preparing a graphene sample on Ir(1 1 1) such that intercalated and non-intercalated regions coexist (i.e.…”

“…By preparing a graphene sample on Ir(1 1 1) such that intercalated and non-intercalated regions coexist (i.e. partial intercalation), Schumacher et al [200,201] showed that nucleation of additional metal (Eu or Cs) is concentrated on top of the pristine areas, while the island density on the intercalated regions is essentially zero.…”

“…In a study by Michely et al, strong selectivity for adsorption of Eu and Cs on pristine G1/Ir(1 1 1), compared to regions intercalated with Eu or Cs, was attributed to the adsorption energy difference between the pristine and modified areas [201]. Nevertheless, it is also necessary to address the question of mass transport, since the deposition process initially distributes adatoms uniformly on intercalated and pristine areas.…”