Wafer-scale graphene quality assessment using micro four-point probe mapping

David M A Mackenzie, Kristoffer Gram Kalhauge, Patrick Rebsdorf Whelan, Frederik W Østergaard, Iwona Pasternak, Wlodek Strupinski, Peter Bøggild, Peter Uhd Jepsen, Dirch Hjorth Petersen

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Abstract

Micro four-point probes (M4PP) provide rapid and automated lithography-free transport properties of planar surfaces including two-dimensional materials. We perform sheet conductance wafer maps of graphene directly grown on a 100 mm diameter SiC wafer using a multiplexed seven-point probe with minor additional measurement time compared to a four-point probe. Comparing the results of three subprobes we find that compared to a single-probe result, our measurement yield increases from 72%-84% to 97%. The additional data allows for correlation analysis between adjacent subprobes, that must measure the same values in case the sample is uniform on the scale of the electrode pitch. We observe that the relative difference in measured sheet conductance between two adjacent subprobes increase in the transition between large and low conductance regions. We mapped sheet conductance of graphene as it changed over several weeks. Terahertz time-domain spectroscopy conductivity maps both before and after M4PP mapping showed no significant change due to M4PP measurement, with both methods showing the same qualitative changes over time.
Original languageEnglish
Article number225709
JournalNanotechnology
Volume31
Issue number22
Number of pages8
ISSN0957-4484
DOIs
Publication statusPublished - 2020

Keywords

  • Graphene
  • SiC
  • Conductance
  • Micro four-point probes
  • Terahertz spectroscopy,
  • Metrology
  • Mapping

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