Lin, Hungyen and Braeuninger-Weimer, Philipp and Kamboj, Varun S. and Jessop, David S. and Degl'innocenti, Riccardo and Beere, Harvey E. and Ritchie, David A. and Zeitler, J. Axel and Hofmann, Stephan (2017) Contactless graphene conductivity mapping on a wide range of substrates with terahertz time-domain reflection spectroscopy. Scientific Reports, 7 (1): 10625. ISSN 2045-2322
Full text not available from this repository.Abstract
We demonstrate how terahertz time-domain spectroscopy (THz-TDS) operating in reflection geometry can be used for quantitative conductivity mapping of large area chemical vapour deposited graphene films on sapphire, silicon dioxide/silicon and germanium. We validate the technique against measurements performed with previously established conventional transmission based THz-TDS and are able to resolve conductivity changes in response to induced back-gate voltages. Compared to the transmission geometry, measurement in reflection mode requires careful alignment and complex analysis, but circumvents the need of a terahertz transparent substrate, potentially enabling fast, contactless, in-line characterisation of graphene films on non-insulating substrates such as germanium.