Real time observation of glass-like carbon formation from SU-8 using X-ray and ultraviolet photoelectron spectroscopy

Astley, Simon, Stritt, Jaspa, Mandal, Soumen ORCID: https://orcid.org/0000-0001-8912-1439, Cuenca, Jerome A. ORCID: https://orcid.org/0000-0003-1370-1167, Evans, D. Andrew and Williams, Oliver A. ORCID: https://orcid.org/0000-0002-7210-3004 2025. Real time observation of glass-like carbon formation from SU-8 using X-ray and ultraviolet photoelectron spectroscopy. Carbon 245 , 120728. 10.1016/j.carbon.2025.120728

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Abstract

The structural development and change in elemental composition of SU-8 3005 photoresist into glass-like carbon due to pyrolysis up to 1000 C is investigated utilising in-situ x-ray and ultraviolet photoelectron spectroscopy (XPS/UPS) under ultra-high vacuum (UHV). XPS spectra were analysed in order to investigate changes to elemental composition and physical structure. Peak asymmetry in the measured C 1s spectra is found to be a clear indicator of a transition in both physical structure and increased electrical conductivity. The in-situ XPS measurement of pyrolysis is effective in isolating changes in oxygen composition solely due to the pyrolysis process. Oxygen concentration, C 1s peak asymmetry and C 1s peak positions are strong indicators of semiconducting SU-8 transitioning to conducting glass-like carbon. For SU-8 pyrolysed above temperatures of 500 C, a clear development is observed in the material structure and composition towards a carbon rich conducting network indicative of glass-like carbon. UPS spectra were analysed to investigate the changes in secondary electron cut-off (SECO) and valence band maximum (VBM) as the SU-8 layer is heated in UHV. The changes in SECO and VBM correlates well with the XPS data and a zero binding energy state is observed at 1000 C.

Item Type:	Article
Date Type:	Publication
Status:	Published
Schools:	Schools > Physics and Astronomy
Publisher:	Elsevier
ISSN:	0008-6223
Funders:	EPSRC
Date of First Compliant Deposit:	28 August 2025
Date of Acceptance:	17 August 2025
Last Modified:	29 Aug 2025 11:15
URI:	https://orca.cardiff.ac.uk/id/eprint/180715

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