High-Contrast Imaging of Graphene via Time-Domain Terahertz Spectroscopy
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We demonstrate terahertz (THz) imaging and spectroscopy of single-layer graphene deposited on an intrinsic Si substrate using THz time-domain spectroscopy. A single-cycle THz pulse undergoes multiple internal reflections within the Si substrate, and the THz absorption by the graphene layer accumulates through the multiple interactions with the graphene/Si interface. We exploit the large absorption of the multiply reflected THz pulses to acquire high-contrast THz images of graphene. We obtain local sheet conductivity of the graphene layer analyzing the transmission data with thin-film Fresnel formula based on the Drude model.
KeywordsGraphene Terahertz imaging Time-domain spectroscopy Multiple internal reflections
The work at Oregon State University was supported by Oregon Nanoscience and Microtechnologies Institute, National Science Foundation (DMR-1063632), and National Research Foundation (NRF) of Korea Grant funded by the Korean Government (NRF-2011-220-D00052) which also supported the work at the Yonsei University. The work at the Yonsei University was supported by the Basic Research Program through the NRF of Korea funded by the Ministry of Education, Science, and Technology (2011-0013255). The work at Cornell was supported by the NSF through the Cornell Center for Materials Research (CCMR), the MARCO Focused Research Center on Materials, Structures, and Devices and the AFOSR. Sample Fabrication was performed at the Cornell node of the National Nanofabrication Infrastructure Network, which is supported by the National Science Foundation (Grant ECS-0335765).
- 1.C. Berger, Z. Song, X. Li, X. Wu, N. Brown, C. Naud, D. Mayou, T. Li, J. Hass, A. N. Marchenkov, E. H. Conrad, P. N. First, and W. A. de Heer, “Electronic confinement and Coherence in Patterned Epitaxial Graphene,” Science 312, 1191-1196 (2006).Google Scholar
- 2.Keun Soo Kim, Yue Zhao, Houk Jang, Sang Yoon Lee, Jong Min Kim, Kwang S. Kim, Jong-Hyun Ahn, Philip Kim, Jae-Young Choi, and Byung Hee Hong, “Large-scale pattern growth of graphene films for stretchable transparent electrodes,” Nature 457, 706-710 (2009).Google Scholar
- 7.S. Bae, H. Kim, Y. Lee, S. Xu, J.-S. Park, Y. Zheng, J. Balakrishnan, T. Lei, H. R. Kim, Y. I. Song, Y. J. Kim, K. S. Kim, B. Özyilmaz, J.-H. Ahn, B. H. Hong, and S. Iijima, “Roll-to-roll production of 30-inch graphene films for transparent electrodes,” Nature Nanotech. 5, 574-578 (2010).CrossRefGoogle Scholar