Neutralization of an epitaxial graphene grown on a SiC(0001) by means of palladium intercalation

Abstract

Pd-intercalated graphene grown on a SiC(0001) substrate was investigated using STM, angle-resolved photoemission spectroscopy, and XPS. Pd atoms deposited at room temperature on a zero layer graphene grown on a SiC(0001) substrate were intercalated between the zero layer graphene and the SiC substrate after the thermal annealing above 700 °C, forming a Pd-intercalated single layer graphene. No charge transfer occurred between the intercalated Pd layer and the graphene, which resulted in the formation of the electrically neutral graphene. The Pd-intercalated graphene remained electrically neutral throughout the annealing temperature range between 700 and 1100 °C. The charge transfer, however, occurred between the intercalated Pd layer and the SiC substrate, which caused a band bending confirmed in the core level spectra measured by XPS.

Epitaxial graphene/silicon carbide intercalation: a minireview on graphene modulation and unique 2D materials

“…Additionally, a shift of approximately 0.7-2.0eV in bulk SiC C 1s and Si 2p peak positions is often observed in the XPS spectrum as a result of intercalation. 9,15,18,[27][28][29][30][31][32][33][34][35] This shift indicates a change in the charge transfer between SiC and EG caused by the presence of an intercalant layer.…”

“…Epitaxial graphene can readily accommodate intercalation. 14,15,18,19,39,40 However, intercalation through pristine, multilayer EG is limited by defects native to the grown graphene layers. Thus, the low defect density afforded by high-temperature EG synthesis techniques can limit the lateral scale of intercalation.…”

“…12 This decoupling is possible with a wide range of intercalant species, including H, O, Ge, and Pd, among others. 9,[13][14][15][16][17][18][19][20] While the precise mechanism of atomic intercalation to the EG/SiC interface is still under investigation, there is experimental evidence that the intercalant atoms diffuse through graphene defects and domain edges to reach to the EG/SiC interface. 9,15,21 In this review we discuss intercalation in EG/SiC systems, highlighting key techniques to realize intercalated EG/SiC materials.…”

Metal Adsorption and Nucleation on Free-Standing Graphene by Low-Energy Electron Point Source Microscopy

“…In general, the type and strength of the bond between metal adsorbate and graphene together with the lateral interaction among adatoms drive the nucleation and growth mode. In the case of alkali metals, the dipole–dipole interaction between atoms leads to two-dimensional growth, at least for submonolayer coverage, ,, while most of the transition metals tend to form three-dimensional clusters at low coverage. ,, …”

“…The formation of such clusters agrees with previously reported experimental results. Scanning-probe measurements have proven that Pd evaporated on highly oriented pyrolytic graphite as well as on supported graphene , at room temperature leads to the formation of spheroidal clusters. However, our experiment does not provide information about the three-dimensionality of the Pd clusters formed on free-standing graphene, nor does it contain evidence for the intercalation of Pd in the bilayer.…”