Evaluation of doped potassium concentrations in stacked Two-Layer graphene using Real-time XPS

Shuichi Ogawa, Yasutaka Tsuda, Tetsuya Sakamoto, Yuki Okigawa, Tomoaki Masuzawa, Akitaka Yoshigoe, Tadashi Abukawa, Takatoshi Yamada

Research output: Contribution to journalArticlepeer-review


The immersion of graphene in potassium hydroxide solutions improves its electron mobility on SiO2/Si substrates. This has been attributed to doping with K atoms, but the K concentration xK has not been determined. Here, xK was determined with X-ray photoelectron spectroscopy using intense synchrotron radiation. The K 2p peak intensity decreased with increasing irradiation time. Curve fitting analysis was performed to quantitatively evaluate the change in xK with irradiation time. However, because the K 2p peak was affected by the asymmetric tail of the C 1 s peak, background removal and peak separation analysis were performed simultaneously using the “active Shirley” method. The change in xK was determined by real-time observations, and xK before irradiation was estimated to be 1.00 ± 0.09 mol %. Furthermore, the C 1 s spectrum shifted to lower binding energy with radiation exposure. This indicated that electron carriers in the graphene decreased because of K desorption.

Original languageEnglish
Article number154748
JournalApplied Surface Science
Publication statusPublished - 2022 Dec 15


  • Active Shirley method
  • Potassium doping
  • Stacked two-layer graphene
  • Synchrotron radiation
  • XPS

ASJC Scopus subject areas

  • Chemistry(all)
  • Condensed Matter Physics
  • Physics and Astronomy(all)
  • Surfaces and Interfaces
  • Surfaces, Coatings and Films


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