  The transmission of the electron across the single normal metal-graphene (NG)
and normal-metal-graphene-normal-metal (NGN) junctions has been investigated.
For the single NG junction, the profile of the maximum transmission which has
been plotted against the dimensionless interface hopping respectively bears
similarity to that of the conductance of the system. The minor effect of the
incidence energy on transmission can also be found in conductance of the single
NG junction whose tunneling behavior poses a striking difference from that of
the NGN junction. Concerning with NGN junction, the transmission and
conductance show more abundant structures when subjected to different incidence
energies, interface hopping, and strain strengths. The increase of strain
strength always induces more resonance peaks at different angles in
transmission and can therefore enhance the conductance. The increase of length
of the middle graphene segment can accommodate more quasi-resonance states,
leading to the more resonance peaks and richer structures in transmission. In
both single NG and NGN junctions, the increase of the wavefunction period on
metal side(s) can be observed due to the enhancement of strain strength, which
can serve as the sensor for the detection of the strain strength in graphene.
