| We report on tunneling processes in transport through graphene-based quantum dots. Due to the special Dirac-like dispersion relation of graphene, Klein tunneling, as known from ultra-relativistic physics, occurs at p-n junctions in the graphene potential landscape: an electron incident on a potential barrier may transmit through the barrier as a hole with probability close to unity. Strictly speaking, the above picture only holds if the discrete graphene lattice is approximated by the continuous Dirac model. In particular, lattice defects or potential variations on the length scale of the lattice spacing break the analogy to the Dirac equation. To assess the role of Klein tunneling in experiment, we simulate transport through a disordered graphene quantum dot as a function of the correlation length of the disorder potential. Our results show that the correlation length plays an essential role in understanding tunneling through realistic graphene-based devices. |
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