  In this paper, we study a theoretical method to calculate the conductance
across a square barrier potential in monolayer graphene. We have obtained an
analytical expression for the transmission coefficient across a potential
barrier for monolayer graphene. Using the transmission coefficient obtained we
have an analytical expression for the conductance. This expression will be used
to calculate the conductance in the case in which there is a potential barrier,
which in our case will modelise the behaviour of a top gate voltage of a field
effect transistor. Once this analysis has been performed we study the scenario
in which carriers scatter with the potential barrier with different incidence
angles and we have found that for any incident angle an effective gap is
induced.
