Fabrication of self-aligned metallic Coulomb blockade devices on Si nanowires

A self-aligned metallic single-electron tunneling transistor was fabricated on a Separated by Implanted Oxygen substrate. An array of 10–50 gold islands of 1–3 nm diameter was isolated between source and drain electrodes on a silicon nanowire. This design reduces the number of transport paths by restricting the number of active nanodots between source and drain. The islands were deposited by a retarding field single ion deposition method, whereby the island sizes and separations could be varied by adjusting landing energy and dose. An undercut beneath the nanowire was used to separate the side gates from the multiple tunnel junction. Coulomb blockade was observed in the source drain characteristics at 77 K.