Patrick R. Whelan: electrical continuity mapping of graphene by terahertz spectroscopy

posted 30 May 2017, 09:16 by Peter Boggild
DTU Nanotech, Technical University of Denmark, Ørsteds Plads 345B, DK-2800 Kongens Lyngby, Denmark.

Large-area characterization of the electrical properties of graphene is of utmost importance in order for graphene to break into the market for transparent conducting electrodes. Terahertz time-domain spectroscopy (THz-TDS) is a non-contact method that can be used to spatially measure electrical properties such as sheet conductance, carrier density, and carrier mobility of graphene. In this talk, I will show that it is possible to gain insights into the spatial distribution of charge carrier scattering mechanisms from THz-TDS and discuss how this relates to the defect density of graphene. Furthermore, I will show examples of how THz-TDS can be used for quality control - for instance by assessing the electrical continuity before graphene is turned into functional devices such as OLEDs. The work has been carried out in collaboration with P. Jepsen, DTU Photonics (Denmark), W. Strupinski, ITME (Poland), C. Huyghebaert, IMEC (Belgium), B. Beyer, Fraunhofer COMEDD (Germany), and A. Ferrari, Cambridge University (UK). 

Patrick R. Whelan is currently a Postdoc in the NanoCarbon group at DTU Nanotech. He primarily works with integration and characterization of large-area graphene with focus on graphene transfers for various applications and THz spectroscopy for non-contact electrical characterization of graphene. He received his BSc in Nanotechnology (2011) and his MSc in Nanophysics (2013) from Aalborg University. He finished his PhD about transfer and characterization of large-area CVD graphene for transparent electrode applications in 2016 at the Technical University of Denmark (DTU Nanotech).