STRENGTHNANO · Strain engineering of atomically-thin nanomembrane-based electromechanical devices

In the proposed project, I will engineer the electronic and mechanical properties of freely suspended 2D crystals such as graphene by strain engineering. Although strain engineering has been aready proposed as a powerful way of fine-tuning the electrical and mechanical properties of 2D crystals to create artificial 2D materials with novel functionalities, experimental studies of the role of strain in the electromechanical properties of 2D crystals are still very scarce.In the first part of the project, I will study the changes in the electronic and mechanical properties of freely suspended ultra-clean graphene flakes while their strain is externally tuned. We will measure changes in the piezoresponse, resonance frequency and quality factor of graphene devices for a broad regime of strains, ranging from compressive to tensile stresses. Special attention will be paid to the case where extreme tensions, close to breaking point, are applied to the graphene crystals.The general character of the experimental setups and techniques that will be developed will also make possible to work with other 2D crystals with properties very different than graphene. Indeed, during the second part of the project, I will modify the electronic properties topological insulators based on Bi2Se3 or Bi2Te3, by means of strain-engineering. Applying such strains will allow us to control the bulk energy band-gap and thus optimize/fine-tune the conduction through the topological surface states.The project is therefore at the forefront of science on graphene-based NEMS and on other interesting 2D nanocrystals, the bismuth-based topological insulators, and will strengthen the visibility of European research in these areas.""