Photocurrent characteristics of nanostructured thin films consisting of surface-modified silicon nanoparticles

We have studied optical and electrical properties in thin films consisting of the network of silicon nanoparticles modified with mercaptosuccinic acid (MSA). A photocurrent measurement system was set up to observe the photocurrent signal as functions of excitation photon energy and power. In addition, we observed the absorption spectra of the thin film and solution of the nanoparticles to clarify the contribution of the nanoparticles structure to the optical transition property. It was found that the photocurrent has an excitation-energy dependence while the profile is different from that of a bulk silicon photodiode. This behaviour suggests the specific photogenerated-carrier transport originating from the structure of the thin film of MSA-modified silicon nanoparticles.