Quantum energy and charging energy in point contact MOSFETs acting as single electron transistors

The charging energy and quantum energy in silicon single electron transistors have been investigated. The devices were fabricated in the form of point contact MOSFETs, some of which show the Coulomb blockade oscillations at room temperature. The charging energy and quantum energy were derived by fitting the simulation results to the experimental data. It was clearly found that the quantum energy became comparable with the charging energy when the dot size is smaller than 10-20 nm and the charging energy is more than 20 meV. These results indicate that the quantum effects should be taken into account even in silicon devices when silicon single electron transistors or MOSFETs smaller than about 20 nm are designed.