Gate tunable non-linear currents in bilayer graphene diodes
  Electric transport of double gated bilayer graphene devices is studied as a function of charge density and bandgap. A top gate electrode can be used to control locally the Fermi level to create a pn junction between the double-gated and single-gated region. These bilayer graphene pn diodes are characterized by non-linear currents and directional current rectification, and we show the rectified direction of the source-drain voltage can be controlled by using gate voltages. A systematic study of the pn junction characteristics allows to extract a gate-dependent bandgap value which ranges from 0 meV to 130 meV. 
Hiroki Shioya, Michihisa Yamamoto, Saverio Russo, Monica F. Craciun   and Seigo Tarucha
cond-mat.mes-hall