Photocurrent generation in random networks of multiwall-carbon-nanotubes grown by an all-laser process

We report photocurrent generation in entangled networks of multiwall-carbon nanotubes (MWCNTs) grown on TiN/Si substrates by an all-laser process. By integrating these MWCNTs into planar devices, we demonstrate that they generate photocurrent over all the visible and near-ultraviolet range, with maximum efficiency around 420 nm. Photocurrent is obtained even at zero applied voltage, pointing to a true photovoltaic (PV) effect. The extracted photocurrent as a function of applied voltage exhibits nonlinear behavior for voltages >= 2 V, suggesting that the devices do not behave as pure photoresistances. Other mechanisms (e.g., Schottky barriers imbalance) are invoked to describe current flow in these PV devices.