Analysis and simulation of coulomb blockade and coulomb diamonds in fullerene single electron transistors

Abstract

The single electron transistor (SET) operates with coulomb blockade phenomena which stops single electron transfer therefore prevents current flow via coulomb barriers in nano scale regime. Coulomb blockade regions are similar to diamond—like regions in SET stability diagram named as coulomb diamonds. Island material has effective role on coulomb diamonds size and coulomb blockade range, so its effect is investigated in this research. SET gold electrodes are designed by Atomistix ToolKit software and then single island SET is simulated by different fullerene molecules. Their V g–V ds characteristics are plotted and compared with together; therefore comparison study indicates that bigger fullerene molecules have less coulomb diamonds area and smaller coulomb blockade range, but C60 and C70 SETs are exempt from this rule which can be explained by quantum degeneracy in the form of lowest unoccupied molecular orbital (LUMOs) that leads to the high electron affinity in C60 and C70 islands. As a result material and diameter of island can tune coulomb blockade range and also coulomb diamonds area in SET.