▎ 摘　　要

Artificial graphene structures embedded in semiconductors could open novel routes for studies of electron interactions in low-dimensional systems. We propose a way to manipulate the transport properties of massless Dirac fermions in an artificial graphene-based tunnel junction. Velocity-modulation control of electron wave propagation in the different regions can be regarded as velocity barriers. Transmission probability of electron is affected profoundly by this velocity barrier. We find that there is no confinement for Dirac electron as the velocity ratio xi is less than 1, but when the velocity ratio is larger than 1 the confined state appears in the continuum band. These localized Dirac electrons may lead to the decreasing of transmission probability.