▎ 摘　　要

We theoretically investigate electron tunneling through a dual-gated graphene heterostructure, in which a thin barrier layer is sandwiched between two graphene layers. We show that the perfect tunneling of electrons presented in a single layer of graphene (also known as Klein tunneling) could be broken in this structure. Moreover, the structure could exhibit a large switching ratio of current, indicating the architecture may be promising for future electronic devices.