Effect of metal contacts on photocurrents in graphene transistors

We present theoretical explanation of photocurrent in graphene and investigate the effect of contact induced states on in-plan electric field in graphene. Contact induced states are similar to the well-known metal induced gap states (MIGS) in metal-semiconductor Schottky junctions, which typically penetrate a few atomic lengths into the semiconductor, while the depth of penetration decreases with increasing band gap. However, in graphene we find that these states penetrate a much longer distance of the order of the width of the contacts.