  We study the effect of the strain on the band structure and the
valley-dependent transport property of graphene heterojunctions. It is found
that valley-dependent separation of electrons can be achieved by utilizing the
strain and on-site energies. In the presence of the strain, the values of the
transmission can be effectively adjusted by changing the strengths of the
strain, while the transport angle basically keeps unchanged. When an extra
on-site energy is simultaneously applied to the central scattering region, not
only are the electrons of valleys K and K' separated into two distinct
transmission lobes in opposite transverse directions, but the transport angles
of two valleys can be significantly changed. Therefore, one can realize an
effective modulation of valley-dependent transport by changing the strength and
stretch angle of the strain and on-site energies, which can be exploited for
graphene-based valleytronics devices.
