Photoinduced Potential Shift of Gold Nanoparticle Overlaid with Photochromic Molecules in the Nano-junction

We fabricated single eletctron tunneling (SET) device structure of photochromic molecule -- gold nanoparticle compound to know the photo irradiation dependence of the electron transport properties. It will be able to detect signals according to structural change of single molecule. Nanogap electrodes were fabricated by using electromigration technique. We measured the properties of the SET devices of molecule -- gold nanoparticle compounds in vacuum prober system. The real-time profile of the source -- drain current (I$_{SD}$) of the SET was measured under irradiation with UV light. I$_{SD}$ indicated a discontinuing jump when SET was irradiated by UV light. This result leads us to the conclusion that the jump of I$_{SD}$ is change of the potential energy of gold nanoparticle due to the photochromism of molecule at single molecular level by UV excitation.