Large-scale production of graphene: Introduction Large-scale - PowerPoint PPT Presentation

Large-scale production of graphene: Introduction

Large-scale production of graphene: what is graphene? Graphene is a truly 2D system made of Carbon atoms arranged in an honeycomb hexagonal lattice Zero-gap semiconductor with a low-energy linear dispersion relation around the Dirac points ⇓ Graphene electrons behave as massless Dirac-like fermions

Large-scale production of graphene: why?

Large-scale production of graphene: why? Typical values for c -Si: indirect gap, bandgap = 1.1242 eV, µ ∼ 500 − 1200 cm 2 V − 1 s − 1 , ρ = 10 5 Ωcm, thermal conductivity = 1.48 Wcm − 1 K − 1 YES NO Direct gap GaAs µ ∼ 4000 − 9000 cm 2 V − 1 s − 1 Technology ρ = 10 9 Ωcm Bandgap ∼ 2-3 eV SiC Price ( > 400 $/wafer) High temperature operation Direct gap Bandgap = 1.75 eV a-Si:H Degradation High absorption coefficient Cheap Bandgap = 5.47 eV Price Diamond µ = 2800 cm 2 V − 1 s − 1 Technology Thermal conductivity = 25 Wcm − 1 K − 1 Direct gap µ ∼ 2 · 10 5 cm 2 V − 1 s − 1 v F ≃ 10 6 m/s Graphene ?? Electric-Field Effect at GHz frequencies Electron concentration ∼ 10 13 / cm 2

Large-scale production of graphene: some pictures

Large-scale production of graphene: perspectives Graphene is a new kind of material exhibiting remarkable, really peculiar and astonishing properties Because of these properties it is regarded as an optimal candidate for future technological applications (touch screen, photovoltaic cells, . . . ), in particular for nano-electronic devices In order to substitute Si-based devices, graphene production techniques -allowing for the synthesis of large-scale area, high reproducible and high transferable graphene flakes- must be improved Our Research Group at I.N.Ri.M. is trying to develop such a technique following different ways: Epitaxial Growth by means of an MBE system, Chemical Vapour Deposition and Carbon implantation/surface segregation