Electron optics in ballistic graphene studied by scanning gate microscopy

par Marco Guerra

Projet de thèse en Physique de la Matière Condensée et du Rayonnement

Sous la direction de Hermann Sellier et de Benjamin (phys) Sacepe.

Thèses en préparation à Grenoble Alpes , dans le cadre de École doctorale physique (Grenoble) , en partenariat avec Institut Néel (laboratoire) depuis le 01-11-2017 .


  • Résumé

    The aim of this PhD is to carry out a detailed transport study of ballistic graphene devices. Due to its outstanding properties, graphene is a very promising material for the future of nano-electronics. The research will be oriented toward the development of electron optics exploiting the unique property of graphene p-n junctions and using scanning gate microscopy (SGM) to perform the imaging of the ballistic electron trajectories. Because of the linear dispersion relation, electrons in graphene behave as mass-less Dirac fermions. The possibility to combine together ballistic effects and Dirac fermions makes graphene the elective material to realize experiments exploiting the effect of negative refraction. It will be carried out a study of how ballistic electrons move in a scenario where the graphene density is modulated by a local gate, thus generating an artificial gate-tunable p-n junction. The technique to obtain ballistic graphene is based on the encapsulation of an exfoliated graphene layer between two boron nitride layers. Combining this high-mobility heterostructure with a bottom graphite gate to create a p-n junction will provide the suitable configuration for the realization of the perfect lens proposed by Veselago. Imaging the electron trajectories will be crucial to understand the exact transmission of the p-n junction. SGM will allow us to perform a real space mapping of these trajectories. This imaging technique is very useful for a complete understanding of the electron transport. This investigation will then open avenues for the realization of new quantum devices being electronic analog of optical components. This PhD work will be carried out at Néel Institute under the supervision of Hermann Sellier and Benjamin Sacépé, respectively experts of SGM and graphene physics.

  • Titre traduit

    Electron optics in ballistic graphene studied by scanning gate microscopy


  • Résumé

    The aim of this PhD is to carry out a detailed transport study of ballistic graphene devices. Due to its outstanding properties, graphene is a very promising material for the future of nano-electronics. The research will be oriented toward the development of electron optics exploiting the unique property of graphene p-n junctions and using scanning gate microscopy (SGM) to perform the imaging of the ballistic electron trajectories. Because of the linear dispersion relation, electrons in graphene behave as mass-less Dirac fermions. The possibility to combine together ballistic effects and Dirac fermions makes graphene the elective material to realize experiments exploiting the effect of negative refraction. It will be carried out a study of how ballistic electrons move in a scenario where the graphene density is modulated by a local gate, thus generating an artificial gate-tunable p-n junction. The technique to obtain ballistic graphene is based on the encapsulation of an exfoliated graphene layer between two boron nitride layers. Combining this high-mobility heterostructure with a bottom graphite gate to create a p-n junction will provide the suitable configuration for the realization of the perfect lens proposed by Veselago. Imaging the electron trajectories will be crucial to understand the exact transmission of the p-n junction. SGM will allow us to perform a real space mapping of these trajectories. This imaging technique is very useful for a complete understanding of the electron transport. This investigation will then open avenues for the realization of new quantum devices being electronic analog of optical components. This PhD work will be carried out at Néel Institute under the supervision of Hermann Sellier and Benjamin Sacépé, respectively experts of SGM and graphene physics.