Abstract-Through-substrate terahertz time-domain reflection spectroscopy for environmental graphene conductivity mapping

Applied Physics Letters

 Hungyen Lin,  Oliver J. Burton, Sebastian Engelbrecht, Kai-Henning Tybussek,  Bernd M. Fischer,  Stephan Hofmann

Schematic of the reflection-based THz-TDS to measure the complex conductivity of graphene through the substrate in a nitrogen purge environment.

https://aip.scitation.org/doi/abs/10.1063/1.5135644

We demonstrate how terahertz time-domain spectroscopy (THz-TDS) operating in reflection geometry can be used for quantitative conductivity mapping of large area chemical vapor deposited graphene films through silicon support. We validate the technique against measurements performed using the established transmission based THz-TDS. Our through-substrate approach allows unhindered access to the graphene top surface and thus, as we discuss, opens up pathways to perform in situ and in-operando THz-TDS using environmental cells.

H.L. acknowledges financial support from the EPSRC (Grant No. EP/R019460/1). S.H. acknowledges funding from the EPSRC (Grant No. EP/K016636/1, GRAPHTED). We also thank Dr. Philipp Braeuninger-Weimer for useful discussion. Additional data for this article are available at https://doi.org/10.17635/lancaster/researchdata/336.