| Autor: |
L. F. Lastras-Martínez, D. Medina-Escobedo, G. Flores-Rangel, R. E. Balderas-Navarro, O. Ruiz-Cigarrillo, R. Castro-García, M. del P. Morales-Morelos, J. Ortega-Gallegos, M. Losurdo |
| Jazyk: |
angličtina |
| Rok vydání: |
2019 |
| Předmět: |
|
| Zdroj: |
AIP Advances, Vol 9, Iss 4, Pp 045309-045309-4 (2019) |
| Druh dokumentu: |
article |
| ISSN: |
2158-3226 |
| DOI: |
10.1063/1.5092339 |
| Popis: |
We report on differential reflectance contrast (DRC) sub-microscopic images measured of graphene layers exfoliated on a SiO2/Si substrate by using a near field scanning optical microscope (NSOM) with a spatial resolution of 40 nm. In general, high-quality mechanically exfoliated graphene flakes have sizes of some micrometers and exhibit a distribution of different thicknesses; thus an approach to characterize the topography of the flakes in the sub-micrometric regime is fundamental. DRC in the near field limit is a very useful technique to characterize the flakes in the sub-microscopic scale. The DRC signal is obtained by taking the numerical difference between the reflectivity coming from a region with no graphene (substrate) and a region containing a graphene layer. It is shown by a multiple reflection model (graphene/SiO2/Si) and spectroscopic ellipsometry measurements that the optical contrast in such system can be modulated by changing the thickness of the SiO2 layer or/and the wavelength of the incident light. The results open the possibility to use this optical technique for the thicknesses characterization in the sub-micrometer scale of 2D materials. |
| Databáze: |
Directory of Open Access Journals |
| Externí odkaz: |
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