Large electron addition energy above 250 meV in a silicon quantum dot in a single-electron transistor

We demonstrate large Coulomb blockade oscillations in a silicon single-electron transistor (Si SET) whose peak-to-valley ratio is about 2 at room temperature. The device is fabricated in the form of a point-contact metal-oxide-semiconductor field-effect transistor (MOSFET) and the gate oxide is formed by chemical vapor deposition (CVD) instead of thermal oxidation. From the analysis of current-voltage characteristics, it is found that the single-electron addition energy is about 259 meV and the dot diameter is less than 4.4 nm. The mechanism of silicon dot formation is also discussed.