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Contactless graphene conductivity mapping on a wide range of substrates with terahertz time-domain reflection spectroscopy.

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.

SUBMITTER: Lin H

PROVIDER: S-EPMC5587735 | biostudies-literature | 2017 Sep

REPOSITORIES: biostudies-literature

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Contactless graphene conductivity mapping on a wide range of substrates with terahertz time-domain reflection spectroscopy.

Lin Hungyen H Braeuninger-Weimer Philipp P Kamboj Varun S VS Jessop David S DS Degl'Innocenti Riccardo R Beere Harvey E HE Ritchie David A DA Zeitler J Axel JA Hofmann Stephan S

Scientific reports 20170906 1

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 geom ...[more]

PMID: 28878213

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