Switching of single-electron oscillations in dual-gated nanocrystalline silicon point-contact transistors

Switching of single-electron transport is observed in point-contact transistors fabricated in nanocrystalline silicon thin films, where the grain size is ∼10 to 40 nm. The effects may be associated with electrostatic coupling between the grains. At 4.2 K, single-electron oscillations in the device current are switched as a function of the voltages on two separate gates. This is investigated further using single-electron Monte Carlo simulation of a model with two charging grains in parallel and intergrain capacitive coupling. A change in the electron number of a grain occurs due to charging of the other grain by a single electron, causing bistable regions in charge stability versus gate voltage. These effects depend not only on the coupling capacitance but also on the cross capacitances between the grains and the two gates.