Graphene tests of Klein phenomena
  Graphene is characterized by chiral electronic excitations. As such it provides a perfect testing ground for the production of Klein pairs (electron/holes). If confirmed, the standard results for barrier phenomena must be reconsidered with, as a byproduct, the accumulation within the barrier of holes. 
Stefano De Leo and Pietro Rotelli
quant-ph cond-mat.mes-hall hep-th