Optical properties of nitrogen-doped graphene thin films probed by spectroscopic ellipsometry

• Published in: Thin solid films Vol. 571; pp. 675 - 679
• Main Authors: Shen, C.C., Tseng, C.C., Lin, C.T., Li, L.J., Liu, H.L.
• Format: Journal Article Conference Proceeding
• Language: English
• Published: Amsterdam Elsevier B.V 28.11.2014; Elsevier
• Subjects: Asymmetry; Chemical vapor deposition; Chemical vapor deposition (including plasma-enhanced cvd, mocvd, etc.); Condensed matter: electronic structure, electrical, magnetic, and optical properties; Cross-disciplinary physics: materials science; rheology; Ellipsometry; Exact sciences and technology; Fullerenes and related materials; diamonds, graphite; Graphene; Instruments, apparatus, components and techniques common to several branches of physics and astronomy; Materials science; Mathematical models; Methods of deposition of films and coatings; film growth and epitaxy; Nitrogen-doped graphene; Optical instruments, equipment and techniques; Optical properties; Optical properties and condensed-matter spectroscopy and other interactions of matter with particles and radiation; Optical properties of specific thin films; Physics; Polarimeters and ellipsometers; Specific materials; Spectroscopy; Surface chemistry; Thin films; Nitrogen-doped graphene; Optical properties; Ellipsometry; Experimental data; Line shape; Spectroscopic ellipsometry; Spectral line shift; Exfoliation; Thin films; CVD; Adsorption; Graphene; Nitrogen additions; Resonance; Absorption spectra; Optical absorption
• ISSN: 0040-6090; 1879-2731
• DOI: 10.1016/j.tsf.2014.05.020

Nitrogen-doped graphene thin films were prepared by either chemical vapor deposition (CVD) or electrochemical exfoliation (ECE). Their optical properties were determined in the spectral region of 0.73–6.42eV and at temperatures between 200 and 350K by spectroscopic ellipsometry. The parameters of the dispersive structures were derived by numerical fitting of the experimental data to the stacked layer model. The optical absorption spectrum of the CVD-grown thin films is characterized by an asymmetric Fano resonance in the ultraviolet frequency region. In contrast, the line shape of the ECE-grown thin films displays less asymmetric. The excitonic resonance of the nitrogen-doped thin films is overall blue shifted by ~0.2–0.3eV compared with that of undoped analog. We interpret these results in terms of the exothermic nature of triazine molecule adsorption due to binding to graphene's surface via electron rich nitrogen. •Optical properties of N-doped graphene films determined by spectroscopic ellipsometry•Fano resonance in the ultraviolet frequency region of all graphene film absorption spectra•Blueshift in the excitonic resonance of N-doped graphene thin films is observed.