Transport Spectroscopy of Donor/Quantum Dot Interactive System in Silicon Nano-Transistors

Donor-atom-based nano-devices in silicon represent a breakthrough for individual control of electrons at atomic scale. Here, a finite-bias characterization of electrical transport through such a device, fabricated on a silicon-on-insulator (SOI) wafer with low phosphorus (P) doping, is presented. In this device, multiple quasi-periodic current peaks are observed at low temperatures in the electrical transfer characteristics. Such behavior of the transport characteristics is generally observed in devices having high doping concentration or with selective doping in the channel region to form a multi-donor cluster quantum dot. However, in the present device donor–cluster formation is highly improbable owing to low doping concentration. The observed electrical transport characteristics of the device are explained with a model of two non-interacting donors coupled in series with an unintentionally larger quantum dot, likely formed within the channel due to roughness. Theoretical simulation is also presented here for such a circuit supporting the experimental observations.