Bias dependent photocurrent characteristics of copper sulfide single nanowires

We studied the photocurrent characteristics of copper sulfide nanowire devices under bias voltages. Under global illumination by a laser beam on the nanowire devices, the magnitude of the photocurrent was often found to be asymmetric with respect to the bias, and in some cases, even the direction of the photocurrent remained unchanged for a bias in the opposite direction. Such an unusual bias dependence can be explained by the asymmetry of the Schottky contacts near the electrodes and by the bias dependent electric field at the contacts, as was confirmed by using scanning photocurrent microscopy.