{"id":117,"date":"2023-10-24T07:33:28","date_gmt":"2023-10-24T07:33:28","guid":{"rendered":"https:\/\/flats.c2n.universite-paris-saclay.fr\/?page_id=117"},"modified":"2024-09-22T16:25:06","modified_gmt":"2024-09-22T16:25:06","slug":"stacking-twisting","status":"publish","type":"page","link":"https:\/\/newflats.c2n.universite-paris-saclay.fr\/?page_id=117","title":{"rendered":"Stacking & Twisting"},"content":{"rendered":"\n

Our experts:<\/mark><\/strong> Jaime Diez Merida<\/a> (LMU), Dmitri Efetov<\/a> (LMU), Maelle Kapfer<\/a> (UPSaclay), Gaia Maffione <\/a>(UPSaclay) and Rebeca Ribeiro-Palau<\/a> (CNRS)<\/p>\n\n\n\n

Clean exfoliated 2D materials are the first step to a great van der Waals heterostructure. There are many tricks to it but the real way to do a great exfoliation is experience! Of course the right type of tape and a clean substrate also help.<\/p>\n\n\n\n

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Exfoliation of BN, graphene and graphite, respectively from left to right, on a Si substrate with 285 nm of thermally grown SiO2<\/sub><\/strong>.<\/strong><\/figcaption><\/figure>\n\n\n\n

Choose your tape:<\/mark> <\/strong>This is a long lasting controversy since many research groups use blue clean room tape and others regular scotch tape. There is not major difference between these two since most of the research groups are able to obtain clean flakes but here once again you should make your own experience and try different tapes since the results can vary depending on the humidity and temperature of the room where you are exfoliating.<\/p>\n\n\n\n

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Photograph of the varieties of tape available. Nitto tapes (A) ELP BT-130E-SL (B) ELPBT-150E-KLand (C )ELPBT-50E-FR along side Ultron tapes (D)1007R-6.0 and (E) 1009R-6.0. Adapted from Daniel Terry’s PhD thesis<\/a><\/strong><\/figcaption><\/figure>\n\n\n\n

Heating technique:<\/mark><\/strong> in order to obtain large area monolayer and bilayer graphene and other 2D materials it is highly recommended to use the technique developed in this article<\/a>. In short, you will need to clean your Si\/SiO2<\/sub> chips in a soft oxygen plasma before approaching the tape with your exfoliated material, once in contact you will need to heat them up in a hot plate at ~100 o<\/sup>C for about 2 minutes, let them cool down after and pill off the tape.<\/p>\n\n\n\n

BN exfoliation: <\/mark><\/strong>for BN exfolaition (not too thin flakes) the process is the same but without heating the substrate before pilling off the tape. Avoiding heating leave cleaner flakes in the case of BN.<\/p>\n\n\n\n

Pro-tips: <\/mark><\/strong><\/p>\n\n\n\n