Orbital mechanism of the circular photogalvanic effect in quantum wells

It is shown that the free-carrier (Drude) absorption of circularly polarized radiation in quantum well structures leads to an electric current flow. The photocurrent reverses its direction upon switching the light helicity. A pure orbital mechanism of such a circular photogalvanic effect is proposed that is based on the interference of different pathways contributing to light absorption. Calculation shows that the magnitude of the helicity-dependent photocurrent in n-doped quantum well structures corresponds to recent experimental observations.