Photocurrent Switching of Monolayer MoS<sub>2</sub> Using a Metal–Insulator Transition

We achieve switching on/off the photocurrent of monolayer molybdenum disulfide (MoS<sub>2</sub>) by controlling the metal–insulator transition (MIT). N-type semiconducting MoS<sub>2</sub> under a large negative gate bias generates a photocurrent attributed to the increase of excess carriers in the conduction band by optical excitation. However, under a large positive gate bias, a phase shift from semiconducting to metallic MoS<sub>2</sub> is caused, and the photocurrent by excess carriers in the conduction band induced by the laser disappears due to enhanced electron–electron scattering. Thus, no photocurrent is detected in metallic MoS<sub>2</sub>. Our results indicate that the photocurrent of MoS<sub>2</sub> can be switched on/off by appropriately controlling the MIT transition by means of gate bias.