Showing posts with label Xin Li. Show all posts
Showing posts with label Xin Li. Show all posts

Saturday, July 7, 2018

Abstract-Conductivity mapping of graphene on polymeric films by terahertz time-domain spectroscopy



Patrick R. Whelan, Deping Huang, David Mackenzie, Sara A. Messina, Zhancheng Li, Xin Li, Yunqing Li, Timothy J. Booth, Peter U. Jepsen, Haofei Shi, Peter Bøggild,

https://www.osapublishing.org/oe/fulltext.cfm?uri=oe-26-14-17748

Fast inline characterization of the electrical properties of graphene on polymeric substrates is an essential requirement for quality control in industrial graphene production. Here we show that it is possible to measure the sheet conductivity of graphene on polymer films by terahertz time-domain spectroscopy (THz-TDS) when all internally reflected echoes in the substrate are taken into consideration. The conductivity measured by THz-TDS is comparable to values obtained from four point probe measurements. THz-TDS maps of 25x30 cm2 area graphene films were recorded and the DC conductivity and carrier scattering time were extracted from the measurements. Additionally, the THz-TDS conductivity maps highlight tears and holes in the graphene film, which are not easily visible by optical inspection.
© 2018 Optical Society of America under the terms of the OSA Open Access Publishing Agreement

Thursday, May 14, 2015

Abstract-Full-range Gate-controlled Terahertz Phase Modulation with Graphene Metasurfaces


Ziqi Miao, Qiong Wu, Xin Li, Qiong He, Kun Ding, Zhenghua An, Yuanbo Zhang, and Lei Zhou
https://www.osapublishing.org/abstract.cfm?uri=CLEO_AT-2015-AF2E.6

Combining metasurfaces with gate controlled graphene, we experimentally demonstrate ±180° phase modulation can be realized at certain frequencies in THz domain, and describe a practical scheme to achieve full-range active phase modulation with such graphene metasurfaces.
© 2015 OSA
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