Charge neutrality and band-gap tuning of epitaxial graphene on SiC by molecular doping
| Autor: | Camilla Coletti, Jurgen H. Smet, C. Riedl, Dong Su Lee, Ulrich Starke, L. Patthey, Benjamin Krauss, K. von Klitzing |
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| Rok vydání: | 2010 |
| Předmět: |
Materials science
Condensed matter physics Photoemission spectroscopy Graphene Fermi level Doping 02 engineering and technology 010402 general chemistry 021001 nanoscience & nanotechnology Condensed Matter Physics 01 natural sciences 7. Clean energy 0104 chemical sciences Electronic Optical and Magnetic Materials law.invention symbols.namesake X-ray photoelectron spectroscopy law symbols 0210 nano-technology Raman spectroscopy Bilayer graphene Ultraviolet photoelectron spectroscopy |
| Zdroj: | Physical Review B. 81 |
| ISSN: | 1550-235X 1098-0121 |
| DOI: | 10.1103/physrevb.81.235401 |
| Popis: | Epitaxial graphene on SiC(0001) suffers from strong intrinsic $n$-type doping. We demonstrate that the excess negative charge can be fully compensated by noncovalently functionalizing graphene with the strong electron-acceptor tetrafluorotetracyanoquinodimethane (F4-TCNQ). Charge neutrality can be reached in monolayer graphene as shown in electron-dispersion spectra from angular-resolved photoemission spectroscopy. In bilayer graphene the band-gap that originates from the SiC/graphene interface dipole increases with increasing F4-TCNQ deposition and, as a consequence of the molecular doping, the Fermi level is shifted into the band-gap. The reduction in the charge-carrier density upon molecular deposition is quantified using electronic Fermi surfaces and Raman spectroscopy. The structural and electronic characteristics of the graphene/F4-TCNQ charge-transfer complex are investigated by x-ray photoelectron spectroscopy and ultraviolet photoelectron spectroscopy. The doping effect on graphene is preserved in air and is temperature resistant up to $200\text{ }\ifmmode^\circ\else\textdegree\fi{}\text{C}$. Furthermore, graphene noncovalent functionalization with F4-TCNQ can be implemented not only via evaporation in ultrahigh vacuum but also by wet chemistry. |
| Databáze: | OpenAIRE |
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