Reversible suppression of Coulomb staircase in InP nanowires with light illumination

Detailed electron transport analysis is performed for an ensemble of conical indium phosphide nanowires bridging two hydrogenated n⁺-silicon electrodes. The current-voltage (I-V) characteristics exhibit a staircase in dark with a period of ~ 1 V at room temperature. The staircase is found to disappear under light illumination. This observation can be explained by assuming the presence of a tiny island within contributing nanowires. Electrons tunnel in and out of the island, resulting in the Coulomb staircase I-V. Applying light illumination raises the electron quasi-Fermi level and the tunneling barriers are buried, causing the Coulomb staircase to disappear.