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Title: Versatile technique for assessing thickness of 2D layered materials by XPS

X-ray photoelectron spectroscopy (XPS) has been utilized as a versatile method for thickness characterization of various two-dimensional (2D) films. Accurate thickness can be measured simultaneously while acquiring XPS data for chemical characterization of 2D films having thickness up to approximately 10 nm. For validating the developed technique, thicknesses of few-layer graphene (FLG), MoS 2 and amorphous boron nitride (a-BN) layer, produced by microwave plasma chemical vapor deposition (MPCVD), plasma enhanced chemical vapor deposition (PECVD), and pulsed laser deposition (PLD) respectively, were accurately measured. The intensity ratio between photoemission peaks recorded for the films (C 1s, Mo 3d, B 1s) and the substrates (Cu 2p, Al 2p, Si 2p) is the primary input parameter for thickness calculation, in addition to the atomic densities of the substrate and the film, and the corresponding electron attenuation length (EAL). The XPS data was used with a proposed model for thickness calculations, which was verified by cross-sectional transmission electron microscope (TEM) measurement of thickness for all the films. The XPS method determines thickness values averaged over an analysis area which is orders of magnitude larger than the typical area in cross-sectional TEM imaging, hence provides an advanced approach for thickness measurement over large areas ofmore » 2D materials. The study confirms that the versatile XPS method allows rapid and reliable assessment of the 2D material thickness and this method can facilitate in tailoring growth conditions for producing very thin 2D materials effectively over a large area. Furthermore, the XPS measurement for a typical 2D material is non-destructive and does not require special sample preparation. Furthermore, after XPS analysis, exactly the same sample can undergo further processing or utilization.« less
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  1. Purdue Univ., West Lafayette, IN (United States)
  2. Air Force Research Lab., WPAFB, OH (United States)
  3. Purdue Univ., West Lafayette, IN (United States); Brookhaven National Lab. (BNL), Upton, NY (United States)
  4. Purdue Univ., West Lafayette, IN (United States); Case Western Reserve Univ., Cleveland, OH (United States)
  5. Purdue Univ., West Lafayette, IN (United States); Air Force Research Lab., WPAFB, OH (United States)
  6. Purdue Univ., West Lafayette, IN (United States); Univ. of Illinois at Urbana-Champaign, Urbana, IL (United States)
  7. Purdue Univ., West Lafayette, IN (United States); Air Force Research Lab., WPAFB, OH (United States); Univ. of California, Los Angeles, CA (United States)
  8. Purdue Univ., West Lafayette, IN (United States); Air Force Research Lab., WPAFB, OH (United States); Univ. of North Texas, Denton, TX (United States)
Publication Date:
Report Number(s):
Journal ID: ISSN 0957-4484
Grant/Contract Number:
Accepted Manuscript
Journal Name:
Additional Journal Information:
Journal Volume: 29; Journal Issue: 11; Journal ID: ISSN 0957-4484
IOP Publishing
Research Org:
Brookhaven National Laboratory (BNL), Upton, NY (United States)
Sponsoring Org:
USDOE Office of Science (SC), Basic Energy Sciences (BES) (SC-22)
Country of Publication:
United States
77 NANOSCIENCE AND NANOTECHNOLOGY; non-destructive measurement; 2D film thickness; few-layer graphene; MoS2 film; amorphous BN film; XPS thickness measurement
OSTI Identifier: