Numerical Study of Very Small Floating Islands

The electrical property of very small floating island whose diameter is less than the de Broglie length is numerically investigated without fitting parameters. In general, it is difficult to well define the capacitance of very small floating islands. In this paper, instead of using the capacitance of islands, the kicking algorithm is applied for simulating the single-electron phenomena of spherical islands (the diameter: ø=0.6, 4, and 6 nm). As a result, the self-potentials of islands are successfully obtained within the precision equivalent to the movement of the sole electron with regard to given gate voltages. In addition, the transient simulation is demonstrated using the dwell time during which an electron is waiting for the next tunneling. The Coulomb blockade is successfully simulated without using the capacitance of very small floating islands. It is also found that trap-assisted tunneling is prohibited by Coulomb blockade at low electric field and can occur at high electric field.