▎ 摘　　要

We calculate the photocurrent in a clean graphene sample normally irradiated by a monochromatic electromagnetic field and subject to a step-like electrostatic potential. We consider the photon energies (h) over bar Omega that significantly exceed the height of the potential barrier, as is the case in the recent experiments with graphene-based photodetectors. The photocurrent comes from the resonant absorption of photons by electrons and decreases with increasing ratio (h) over bar Omega/U-0. It is weakly affected by the background gate voltage and depends on the light polarization as proportional to sin(2) gamma, gamma being the angle between the potential step and the polarization plane.