Mapping nanoscale carrier confinement in polycrystalline graphene by terahertz spectroscopy
Abstract Terahertz time-domain spectroscopy (THz-TDS) can be used to map spatial variations in electrical properties such as sheet conductivity, carrier density, and carrier mobility in graphene. Here, we consider wafer-scale graphene grown on germanium by chemical vapor deposition with non-uniformi...
| Main Authors: | , , , , , , , , , , , , , , |
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| Format: | Article |
| Language: | English |
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Nature Portfolio
2024-02-01
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| Series: | Scientific Reports |
| Online Access: | https://doi.org/10.1038/s41598-024-51548-z |
| _version_ | 1797274836306755584 |
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| author | Patrick R. Whelan Domenico De Fazio Iwona Pasternak Joachim D. Thomsen Steffen Zelzer Martin O. Mikkelsen Timothy J. Booth Lars Diekhöner Ugo Sassi Duncan Johnstone Paul A. Midgley Wlodek Strupinski Peter U. Jepsen Andrea C. Ferrari Peter Bøggild |
| author_facet | Patrick R. Whelan Domenico De Fazio Iwona Pasternak Joachim D. Thomsen Steffen Zelzer Martin O. Mikkelsen Timothy J. Booth Lars Diekhöner Ugo Sassi Duncan Johnstone Paul A. Midgley Wlodek Strupinski Peter U. Jepsen Andrea C. Ferrari Peter Bøggild |
| author_sort | Patrick R. Whelan |
| collection | DOAJ |
| description | Abstract Terahertz time-domain spectroscopy (THz-TDS) can be used to map spatial variations in electrical properties such as sheet conductivity, carrier density, and carrier mobility in graphene. Here, we consider wafer-scale graphene grown on germanium by chemical vapor deposition with non-uniformities and small domains due to reconstructions of the substrate during growth. The THz conductivity spectrum matches the predictions of the phenomenological Drude–Smith model for conductors with non-isotropic scattering caused by backscattering from boundaries and line defects. We compare the charge carrier mean free path determined by THz-TDS with the average defect distance assessed by Raman spectroscopy, and the grain boundary dimensions as determined by transmission electron microscopy. The results indicate that even small angle orientation variations below 5° within graphene grains influence the scattering behavior, consistent with significant backscattering contributions from grain boundaries. |
| first_indexed | 2024-03-07T15:03:50Z |
| format | Article |
| id | doaj.art-f221f236947e4dd5af7fcbd8f77ad5cc |
| institution | Directory Open Access Journal |
| issn | 2045-2322 |
| language | English |
| last_indexed | 2024-03-07T15:03:50Z |
| publishDate | 2024-02-01 |
| publisher | Nature Portfolio |
| record_format | Article |
| series | Scientific Reports |
| spelling | doaj.art-f221f236947e4dd5af7fcbd8f77ad5cc2024-03-05T19:00:27ZengNature PortfolioScientific Reports2045-23222024-02-011411910.1038/s41598-024-51548-zMapping nanoscale carrier confinement in polycrystalline graphene by terahertz spectroscopyPatrick R. Whelan0Domenico De Fazio1Iwona Pasternak2Joachim D. Thomsen3Steffen Zelzer4Martin O. Mikkelsen5Timothy J. Booth6Lars Diekhöner7Ugo Sassi8Duncan Johnstone9Paul A. Midgley10Wlodek Strupinski11Peter U. Jepsen12Andrea C. Ferrari13Peter Bøggild14DTU Physics, Technical University of DenmarkCambridge Graphene Centre, University of CambridgeFaculty of Physics, Warsaw University of TechnologyDTU Physics, Technical University of DenmarkDepartment of Materials and Production, Aalborg UniversityDepartment of Materials and Production, Aalborg UniversityDTU Physics, Technical University of DenmarkDepartment of Materials and Production, Aalborg UniversityCambridge Graphene Centre, University of CambridgeDepartment of Materials Science and Metallurgy, University of CambridgeDepartment of Materials Science and Metallurgy, University of CambridgeFaculty of Physics, Warsaw University of TechnologyCenter for Nanostructured Graphene (CNG), Technical University of DenmarkCambridge Graphene Centre, University of CambridgeDTU Physics, Technical University of DenmarkAbstract Terahertz time-domain spectroscopy (THz-TDS) can be used to map spatial variations in electrical properties such as sheet conductivity, carrier density, and carrier mobility in graphene. Here, we consider wafer-scale graphene grown on germanium by chemical vapor deposition with non-uniformities and small domains due to reconstructions of the substrate during growth. The THz conductivity spectrum matches the predictions of the phenomenological Drude–Smith model for conductors with non-isotropic scattering caused by backscattering from boundaries and line defects. We compare the charge carrier mean free path determined by THz-TDS with the average defect distance assessed by Raman spectroscopy, and the grain boundary dimensions as determined by transmission electron microscopy. The results indicate that even small angle orientation variations below 5° within graphene grains influence the scattering behavior, consistent with significant backscattering contributions from grain boundaries.https://doi.org/10.1038/s41598-024-51548-z |
| spellingShingle | Patrick R. Whelan Domenico De Fazio Iwona Pasternak Joachim D. Thomsen Steffen Zelzer Martin O. Mikkelsen Timothy J. Booth Lars Diekhöner Ugo Sassi Duncan Johnstone Paul A. Midgley Wlodek Strupinski Peter U. Jepsen Andrea C. Ferrari Peter Bøggild Mapping nanoscale carrier confinement in polycrystalline graphene by terahertz spectroscopy Scientific Reports |
| title | Mapping nanoscale carrier confinement in polycrystalline graphene by terahertz spectroscopy |
| title_full | Mapping nanoscale carrier confinement in polycrystalline graphene by terahertz spectroscopy |
| title_fullStr | Mapping nanoscale carrier confinement in polycrystalline graphene by terahertz spectroscopy |
| title_full_unstemmed | Mapping nanoscale carrier confinement in polycrystalline graphene by terahertz spectroscopy |
| title_short | Mapping nanoscale carrier confinement in polycrystalline graphene by terahertz spectroscopy |
| title_sort | mapping nanoscale carrier confinement in polycrystalline graphene by terahertz spectroscopy |
| url | https://doi.org/10.1038/s41598-024-51548-z |
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