Room temperature operation of a-C based single electron transistors

Room temperature operations of single electron transistors (SETs) were realized with amorphous carbon (a-C) based SETs. SETs are promising devices for solving power dissipation problems, as each electron is controlled individually. They are now attracting much attention and are being studied from many perspectives, especially their fabrication processes. In this study, double tunnel junctions consisting of a-C wires and a dot with a WC/sub x/ gate electrode were fabricated for three-terminal device operation to demonstrate the feasibility of our methods. In the gate between the Nb source and drain electrodes, fine WC/sub x/ electrodes were deposited using the FIB system. These WC/sub x/ wires act as the leads from the dull edge of Nb electrodes to the microscopic a-C electrodes. The WC/sub x/ gate was then deposited to form a side-gate structure with about a 1 μm gap between the gate and the tunnel junction. Finally, a-C wires and a dot were deposited using the SEM system. The width and diameter of the a-C wires and dot were about 40 nm. The gaps between a-C wires and dot were about 50 nm which means that the air gap is the potential barrier for each electron. Experimental results show that we successfully fabricated SETs with nanostructure a-C wires and dot and clearly recorded single-electron charging effects at room temperature. This result is to the authors' knowledge the first demonstration of such a device fabricated by beam-induced reaction processes.