Enhancement of photocurrent in suspended monolayer graphene

The photocurrent in graphene has drawn much attention in recent years. The mechanisms of its production vary in different situations, such as at the interfaces of monolayer-bilayer junction or p-n junction. Here we demonstrate photocurrent generation in graphene-based field-effect transistors (GFETs) with a partially suspended area. Both Raman and photocurrent mapping were performed after a laser-induced doping under vacuum at room temperature. The resulting photocurrent in the suspended area is an order of magnitude larger than that in the supported area. The difference in photocurrent may be attributed to the thermoelectric effect.