Elucidating the influence of residual polymer and gas environment on the electronic structure of a graphene layer using in situ APXPS

• Published in: Applied surface science Vol. 528; no. C; p. 146764
• Main Authors: Yun, Dong-Jin, Etxebarria, Ane, Lee, Kyung-Jae, Jung, Changhoon, Ko, Dong-Su, Seol, Min-Su, Kim, Hae-ryong, Jeon, Woo-Sung, Lee, Eunha, Chung, JaeGwan, Crumlin, Ethan J.
• Format: Journal Article
• Language: English
• Published: Netherlands Elsevier B.V 30.10.2020; Elsevier
• Subjects: Ambient pressure X-ray photoelectron spectroscopy; Electronic structure; Graphene; Ultraviolet photoelectron spectroscopy; Work function; Ambient pressure X-ray photoelectron spectroscopy; Electronic structure; Work function; Graphene; Ultraviolet photoelectron spectroscopy
• ISSN: 0169-4332; 1873-5584
• DOI: 10.1016/j.apsusc.2020.146764

[Display omitted] •Designing the APXPS analysis to characterize the graphene electronic structure under real gas environment.•Clarifying the differences in influence between the organic residue on Gr and gas environment on the Gr electronic structure.•Verification of the reliability of APXPS for the electronic structure change in Gr at controlled gas environment.•Verification of little change in Gr chemical/electronic structure despite heat treatment in near ambient gas environment. We use in situ ambient pressure X-ray photoelectron spectroscopy (APXPS) and ultraviolet photoelectron spectroscopy (UPS) to develop an effective method for studying changes in the graphene (Gr) electronic structure according to certain circumstance. The amount of polymethyl methacrylate (PMMA) residual polymer (RP), inevitably generated during the Gr transfer process, is significantly reduced from Gr surface by thermal annealing. This processed Gr is then sequentially exposed to specific gas environments (Ar, N2, O2, and CO2), and APXPS or UPS is carried out to investigate the variations in the Gr electronic structure including the work function. When the amount of PMMA RP on Gr is reduced, the position of the main carbon peak shifts by >0.4 eV to a higher binding energy (in XPS spectra), and the secondary electron cutoff moves by about 0.2 eV to a lower binding energy (in UPS spectra). These changes are generally caused by a decrease in the Gr work function. On the other hand, exposure to the gas environments at different temperatures that we investigated did not produce significant changes in the work function and chemical states of Gr. These results confirm that the material in contact with Gr should be considered to achieve the desired Gr performance in electronics.