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Infrared transmission spectroscopy of CVD graphene on Si
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Paper Abstract

We report transmission spectroscopy results from the mid- to far-infrared on graphene, grown by chemical vapor deposition (CVD) on Cu. Similar results have been reported by several groups and their substrates of choice were thermal Si dioxide, quartz, or SiC, where strong phonon absorption results in transmission blocking bands in midinfrared. Silicon wafers (thickness ~ 500 μm), on the other hand, have transmission extending out to about 100 cm-1 when the doping level is low. Therefore, we choose to use Si wafers as the carrier substrates for transferred CVD graphene. The complex refractive index of the Si substrate is measured by infrared spectroscopic ellipsometry. As a result, continuous spectra (without blocking bands) in the range of 400 to 4000 cm-1 are obtained and they are modeled by free carrier absorption (the Drude model) and interband transitions (considering the Pauli blocking.) From these, the carrier density, carrier mobility, sheet resistivity, intraband scattering rate, and graphene layer number can be inferred. In the far-infrared range, the absorption is dominated by the intraband free carrier absorption and it mainly results from the interband transition in the mid-infrared range. Having continuous spectra using the Si substrates gives us the advantage to model the whole spectral region (from far-infrared to mid-infrared) accurately.

Paper Details

Date Published: 27 September 2012
PDF: 6 pages
Proc. SPIE 8462, Carbon Nanotubes, Graphene, and Associated Devices V, 84620H (27 September 2012); doi: 10.1117/12.930246
Show Author Affiliations
Shin Mou, Air Force Research Lab. (United States)
Steve S. Kim, Air Force Research Lab. (United States)
Kuei-Hsien Chen, Academia Sinica (Taiwan)
Li-Chyong Chen, National Taiwan Univ. (Taiwan)
Rajesh R Naik, Air Force Research Lab. (United States)
Gail J. Brown, Air Force Research Lab. (United States)
W. C. Mitchel, Air Force Research Lab. (United States)

Published in SPIE Proceedings Vol. 8462:
Carbon Nanotubes, Graphene, and Associated Devices V
Didier Pribat; Young-Hee Lee; Manijeh Razeghi, Editor(s)

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