Holler, Johannes and Bauriedl, Lorenz and Korn, Tobias and Seitz, Andrea and Oezyigit, Furkan and Eichinger, Michaela and Schueller, Christian and Watanabe, Kenji and Taniguchi, Takashi and Strunk, Christoph and Paradiso, Nicola (2020) Air tightness of hBN encapsulation and its impact on Raman spectroscopy of van der Waals materials. 2D MATERIALS, 7 (1): 015012. ISSN 2053-1583,
Full text not available from this repository. (Request a copy)Abstract
Raman spectroscopy is a precious tool for the characterization of van der Waals materials, e.g. for the determination of the layer number in thin exfoliated flakes. For sensitive materials, however, this method can be dramatically invasive. In particular, the light intensity required to obtain a significant Raman signal is sufficient to immediately photo-oxidize few-layer thick metallic van der Waals materials. In this work we investigated the impact of the environment on Raman characterization of thin NbSe2 crystals. We show that in ambient conditions the flake is locally oxidized even for very low illumination intensity. Based on this extreme sensitivity to the presence of light and oxygen, we could study the air-tightness of the hBN encapsulation method, the most common passivation method for a wide range of 2D material-based devices. We find that only fully encapsulated devices are reliably air-tight. On the contrary, a simple hBN cover from the top does not prevent a slow diffusion of oxygen between the SiO2 surface and the flake itself.
| Item Type: | Article |
|---|---|
| Uncontrolled Keywords: | PASSIVATION; Raman spectroscopy; sensitive 2D materials; photo-oxidation; hBN encapsulation; niobium diselenide |
| Subjects: | 500 Science > 530 Physics |
| Divisions: | Physics > Institute of Experimental and Applied Physics > Chair Professor Lupton > Group Christian Schüller Physics > Institute of Experimental and Applied Physics > Chair Professor Weiss > Group Christoph Strunk |
| Depositing User: | Dr. Gernot Deinzer |
| Date Deposited: | 08 Mar 2021 06:13 |
| Last Modified: | 08 Mar 2021 06:13 |
| URI: | https://pred.uni-regensburg.de/id/eprint/45563 |
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