Tunneling characteristics of graphene
Negative differential conductance and tunneling characteristics of two-terminal graphene devices are observed before and after electric breakdown, respectively. The former is caused by the strong scattering under a high E-field, and the latter is due to the appearance of a tunneling barrier in graphene channel induced by a structural transformation from crystalline graphene to disordered graphene because of the breakdown. Using Raman spectroscopy and imaging, the presence of nonuniform disordered graphene is confirmed. A memory switching effect of 100 000% ON/OFF ratio is demonstrated in the tunneling regime, which can be employed in various applications.