Observation of Single Electron-Hole Recombination and Photon-Pumped Current in an Asymmetric Si Single-Electron Transistor

We observed a novel type of photocurrent by investigating Coulomb blockade oscillations around the few-electron regime in an asymmetric Si single-electron transistor. Photoexcitation generates new current peaks below the threshold voltage only for one polarity of source-drain voltage. Under low excitation, such photocurrent exhibits intermittent behavior with sudden drops and rises. The phenomena can be ascribed to the interplay of photogenerated holes and single-electron tunneling via the island. The sudden drop is a manifestation of single-electron recombination with a hole in the island.