Graphène et BN bientôt inséparables ? "Le BN sera au graphène ce que le SiO2 est au Si, en mieux !" Ou encore : "Si le graphène sert un jour à quelque chose, ce sera grâce au BN !" (P. Dollfus, 13 octobre 2011) Institute for Fundamental Electronics, CNRS, University of Paris-Sud, Orsay, France http://computational-electronics.ief.u-psud.fr/

The best : suspended graphene T = 5 K SiO2 substrate: µmax = 25000 cm2/Vs Suspended: µmax = 230000 cm2/Vs

But,…  However, suspended graphene is not suitable for applications Need for insulating substrate  Standardly used substrate: SiO2 - Compatible with standard processing facilities  - Many problems or limitations (mobility):  - surface roughness - scattering by charged surface states and impurities  Epitaxial Graphene on SiC - Mobility not better than for G reported on SiO2 - Thickness (number of layers) difficult to control - Poor uniformity - Possibility of bandgap ?? (controversy)

The advantages of h-BN substrates  The future of graphene: h-BN substrate Xue, Nature Mat. 2011 Same lattice structure, very small lattice mismatch (1.7%) - Free of dangling bonds and surface charge traps - Smooth surface - EG (BN) = 5.97 eV Giovanetti, PRB 2007 (+ bandgap opening in graphene: 53 meV)

The advantages of h-BN substrates Monolayer: µ = 60000 cm2/Vs (electrons) and Bilayer: µ = 60000 cm2/Vs (electrons) and 80000 cm2/Vs (holes) EG  0

Avoiding mechanical transfer ? Yes ! et al. Et ça marche…

Avoiding mechanical transfer ? Yes  h-BN as gate insulator (even double-gate ?)

Graphene / h-BN stacks (other information in Zhao Physica E 43 (2010) 440

Towards graphene/h-BN heterostructures

Graphene/h-BN heterostructures

Graphene/h-BN heterostructures

Future works ? By means of tight-binding description of the full device  Graphene transistors with single or double BN gate  RTD in in-plane G-BN-G-BN-G structures Alternative to: - nanostructuration of GNRs with different sections - doping to generate barriers