Temperature-dependent transport properties of graphene decorated by alkali metal adatoms (Li, K)

Abstract

We report the electrical transport properties of graphene for dilute alkali metal decoration (n ∼ 2 × 1012 cm−2) at cryogenic temperatures. Upon deposition of K and Li atoms at T = 20 K, graphene devices are doped with electrons, and the charge carrier mobility is decreased. As temperature is increased, the number of electrons donated to the graphene and the number of charged scatterers are reduced, and the mobility of the metal decorated graphene is increased. This differs from the typical temperature-dependent transport in undecorated graphene, where the mobility decreases with increasing temperature. To investigate the kinetic behavior of adatoms on graphene, we estimate the hopping time of the Li and K adatoms on graphene based on the migration barrier in the low concentration regime of the metal adatoms by Density Functional Theory calculations. The calculations reveal that these adatoms are mobile even at cryogenic temperatures and become more mobile with increasing temperature, allowing for cluster formation of adatoms. This indicates that the dominant factor in the electron transport on warming is a cluster formation.

Tailoring Intercalant Assemblies at the Graphene–Metal Interface

“…It is therefore not surprising that many aspects of alkali metal adsorption have been studied, e. g., the geometric structure of superlattices, [76][77][78][79][80][81] vibrational quanta, [82][83][84][85] and lifetimes of electronic excitations [86][87][88][89][90][91][92] On graphene, adsorption of alkali metals was shown to, e. g., tune the band gap opening between the graphene Dirac cones 93,94 and modify the electronic transport. 95,96 More recently, the intercalation of alkali metals on graphene-covered surfaces has moved into a focus of surface science research. For instance, doping of graphene on Ir(111) may be controlled by the intercalation of Cs.…”

“…The adsorption of alkali metals on surfaces has a longstanding tradition in surface science. − The promotion of catalytic reactions − and the increase of electron emission rates belong to the appealing alkali-induced effects. It is therefore not surprising that many aspects of alkali metal adsorption have been studied, for example, the geometric structure of superlattices, − vibrational quanta, − and lifetimes of electronic excitations. − On graphene, adsorption of alkali metals was shown to, for example, tune the band gap opening between the graphene Dirac cones , and modify the electronic transport. , …”

“…86−92 On graphene, adsorption of alkali metals was shown to, for example, tune the band gap opening between the graphene Dirac cones 93,94 and modify the electronic transport. 95,96 More recently, the intercalation of alkali metals on graphenecovered surfaces has moved into a focus of surface science research. For instance, doping of graphene on Ir(111) may be controlled by the intercalation of Cs.…”

Spin–orbit proximity effect in graphene on metallic substrates: decoration versus intercalation with metal adatoms

“…The first case should induce changes mainly in the G's properties already perturbed by the metal surface, while the latter might significantly alter the graphene-substrate proximity, as graphene will now interact with the metal mainly via the intercalated adatom. Importantly, both decoration and intercalation can be realized experimentally [12][13][14][15][16][17][18][19][20][21][22][23] and are known to provide several interesting options for engineering of graphene's properties, in addition to any possible enhancement of SOC [24]. Here, we will focus on two previously studied models, G/Pt(111) and G/Au/Ni(111) which present markedly different electronic and magnetic properties, and consider the adsorption of one species for each system, namely, a Pt adatom for G/Pt(111) and an Au adatom for G/Au/Ni(111).…”

Superconducting Phases in Lithium Decorated Graphene LiC6

“…Evidence of superconductivity in Li-decorated few layer graphene at 7.4 K has been reported by Tiwari and collaborators 7 . Low temperature mobility of K and Li atoms on graphene was observed by Woo et al ., and suggest that mobility may persist at lower temperatures 8 , which would provide new challenges for theory.…”