Graphene etching

ANR CleanGRAPH, coordinated by the LTM from 2013 to 2016, we showed experimentally that this was possible with an ICP plasma (by very special AlF3 conditioning of the reactor to avoid the presence of impurities in the plasma ), thus removing a technological obstacle to the integration of CVD graphene in devices (Fig. 8a-b). The infinite etching selectivity between PMMA and graphene is due to the sp2 hybridization of graphene which allows it to resist low energy ions (< 13 eV) and the attack of H radicals (a potential barrier prevents their chemisorption) . We also structured graphene to fabricate networks of graphene nanoribbons (transistor channel) using block copolymers as an etching mask, as depicted here below :

a) HRTEM of CVD graphene after 150 s of H2 plasma which shows clean and gap-free graphene. B) Band structure measured by kPEEM showing a Dirac cone. c) STEM section of PDMS/PS block copolymers above graphene. The PDMS cylinders are revealed in O2 plasma and serve as a mask for the etching of graphene nanoribbons.

We finally think that the implantation of He should make it possible to exfoliate the graphene or to etch it layer by layer (Patent): the He atoms which are implanted form a gas between the substrate and the graphene leading to its lift-off . All of this work gives the team unique know-how in the popular field of 2D materials.