Fabrication and characterization of Quantum Materials: Graphene heterostructures and Topological Insulators

Abstract

Fabrication and characterization of Quantum Materials: Graphene heterostructures and Topological Insulators by Vito CLERICÒ Starting from a detailed description of the Clean Room facilities, installed during this thesis work, we report the fabrication processes based on graphene and other 2D materials in detail. In hBN-encapsulated graphene the Quantum Hall Effect (QHE) at room temperature and high magnetic field was observed. We found different features in the QHE respect a previous work on lower mobility graphene on silicon oxide (Novoselov et al. Science 315 1379 2007). A detalied study of transport properties in graphene nanoconstrictions is also reported. In particular in encapsulated graphene we introduced a new cryo-etching method to obtain low roughness edges nanocostrictions, in which quantized conductance was observed. In the last part of the thesis we report transport measurements on InAs/GaSb double quantum wells with different bandgap configurations (inverted, normal or critical). v Contents Acknowledgements v