Electrical characteristics of Si single-electron transistor based on multiple islands

We investigated the electrical characteristics specifically associated with cotunneling and quantum effects of single-electron transistors (SETs) with three geometrically defined islands. Clear Coulomb oscillation and negative differential conductance were observed. The drain current for the peaks and valleys of the Coulomb oscillation was measured as a function of temperature and drain voltage. Consequently, it was found that the valley current was well described by the inelastic cotunneling theory at temperatures above 40 K in the low-drain-voltage region; on the other hand, elastic cotunneling dominantly contributed to the valley current in the low-temperature and low-drain-voltage region. However, for a high gate voltage, the SET behaved as a single-island device. This is probably because the three islands were electrically enlarged and merged into a single island owing to the high applied gate voltage.