title: Noninvasive Scanning Raman Spectroscopy and Tomography for Graphene Membrane Characterization.
abstract: Graphene has extraordinary mechanical and electronic properties, making it a promising material for membrane-based nanoelectromechanical systems (NEMS). Here, chemical-vapor-deposited graphene is transferred onto target substrates to suspend it over cavities and trenches for pressure-sensor applications. The development of such devices requires suitable metrology methods, i.e., large-scale characterization techniques, to confirm and analyze successful graphene transfer with intact suspended graphene membranes. We propose fast and noninvasive Raman spectroscopy mapping to distinguish between free-standing and substrate-supported graphene, utilizing the different strain and doping levels. The technique is expanded to combine two-dimensional area scans with cross-sectional Raman spectroscopy, resulting in three-dimensional Raman tomography of membrane-based graphene NEMS. The potential of Raman tomography for in-line monitoring is further demonstrated with a methodology for automated data analysis to spatially resolve the material composition in micrometer-scale integrated devices, including free-standing and substrate-supported graphene. Raman tomography may be applied to devices composed of other two-dimensional materials as well as silicon micro- and nanoelectromechanical systems.
authors.affiliation: Department of Electrical Engineering and Computer Science, University of Siegen , Hölderlinstrasse 3, 57076 Siegen, Germany.
authors.forename: Stefan
authors.identifier: 0000-0002-6799-6709
authors.initials: S
authors.lastname: Wagner
authors.affiliation: WITec Wissenschaftliche Instrumente und Technologie GmbH , Lise-Meitner-Strasse 6, 89081 Ulm, Germany.
authors.forename: Thomas
authors.initials: T
authors.lastname: Dieing
authors.affiliation: Graphenea S.A. , Avenida de Tolosa 76, 20018 San Sebastián, Spain.
authors.forename: Alba
authors.initials: A
authors.lastname: Centeno
authors.affiliation: Graphenea S.A. , Avenida de Tolosa 76, 20018 San Sebastián, Spain.
authors.forename: Amaia
authors.initials: A
authors.lastname: Zurutuza
authors.affiliation: School of Information and Communication Technology, KTH Royal Institute of Technology , E229, 16440 Kista, Sweden.
authors.forename: Anderson D
authors.identifier: 0000-0003-4637-8001
authors.initials: AD
authors.lastname: Smith
authors.affiliation: School of Information and Communication Technology, KTH Royal Institute of Technology , E229, 16440 Kista, Sweden.
authors.forename: Mikael
authors.initials: M
authors.lastname: Östling
authors.affiliation: Department of Electrical Engineering and Computer Science, University of Siegen , Hölderlinstrasse 3, 57076 Siegen, Germany.
authors.forename: Satender
authors.initials: S
authors.lastname: Kataria
authors.affiliation: Department of Electrical Engineering and Computer Science, University of Siegen , Hölderlinstrasse 3, 57076 Siegen, Germany.
authors.forename: Max C
authors.identifier: 0000-0003-4552-2411
authors.initials: MC
authors.lastname: Lemme
keywords: 2D materials; MEMS; NEMS; Raman spectroscopy; Raman tomography; doping; nanoelectromechanical systems; noninvasive; strain; suspended graphene