Freestanding n-Doped Graphene via Intercalation of Calcium and Magnesium into the Buffer Layer-SiC(0001) Interface
| Autor: | Matthew T. Dejarld, Yuefeng Yin, Anton Tadich, Antonija Grubišić-Čabo, Nikhil V. Medhekar, Rachael L. Myers-Ward, Jimmy C. Kotsakidis, D. Kurt Gaskill, Marc Currie, Michael S. Fuhrer, Amadeo L. Vázquez de Parga, Shojan P. Pavunny, Kevin M. Daniels, Chang Liu, Mark T. Edmonds |
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| Jazyk: | angličtina |
| Rok vydání: | 2020 |
| Předmět: |
endocrine system
Materials science General Chemical Engineering Intercalation (chemistry) FOS: Physical sciences chemistry.chemical_element 02 engineering and technology Calcium 010402 general chemistry 01 natural sciences Buffer (optical fiber) Superconductivity (cond-mat.supr-con) stomatognathic system Materials Chemistry Condensed Matter - Materials Science Magnesium Condensed Matter - Superconductivity Materials Science (cond-mat.mtrl-sci) General Chemistry 021001 nanoscience & nanotechnology eye diseases 0104 chemical sciences 3. Good health chemistry Chemical engineering Epitaxial graphene Doped graphene 0210 nano-technology Layer (electronics) |
| Zdroj: | Repositorio Institucional del Instituto Madrileño de Estudios Avanzados en Nanociencia instname |
| Popis: | The intercalation of epitaxial graphene on SiC(0001) with Ca has been studied extensively, yet precisely where the Ca resides remains elusive. Furthermore, the intercalation of Mg underneath epitaxial graphene on SiC(0001) has not been reported. Here, we use low energy electron diffraction, x-ray photoelectron spectroscopy, secondary electron cut-off photoemission and scanning tunneling microscopy to elucidate the physical and electronic structure of both Ca- and Mg-intercalated epitaxial graphene on 6H-SiC(0001). We find that Ca intercalates underneath the buffer layer and bonds to the Si-terminated SiC surface, breaking the C-Si bonds of the buffer layer i.e. 'freestanding' the buffer layer to form Ca-intercalated quasi-freestanding bilayer graphene (Ca-QFSBLG). The situation is similar for the Mg-intercalation of epitaxial graphene on SiC(0001), where an ordered Mg-terminated reconstruction at the SiC surface and Mg bonds to the Si-terminated SiC surface are formed, resulting in Mg-intercalated quasi-freestanding bilayer graphene (Mg-QFSBLG). Ca-intercalation underneath the buffer layer has not been considered in previous studies of Ca-intercalated epitaxial graphene. Furthermore, we find no evidence that either Ca or Mg intercalates between graphene layers. However, we do find that both Ca-QFSBLG and Mg-QFSBLG exhibit very low workfunctions of 3.68 and 3.78 eV, respectively, indicating high n-type doping. Upon exposure to ambient conditions, we find Ca-QFSBLG degrades rapidly, whereas Mg-QFSBLG remains remarkably stable. 58 pages, 10 figures, 4 tables. Revised text and figures |
| Databáze: | OpenAIRE |
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