  We have investigated the transmission in monolayer graphene barrier at
nonzero angle of incidence. Taking the influence of parallel wave vector into
account, the transmission as the function of incidence energy has a gap due to
the evanescent waves in two cases of Klein tunneling and classical motion. The
modulation of the transmission gap by the incidence angle, the height, and
width of potential barrier may lead to potential applications in graphene-based
electronic devices.
