Single electron electronics: Challenge for nanofabrication

Abstract

Single electronics has the potential to overcome the limitations of complementary metal oxide semiconductor (CMOS) technology as device dimensions shrink towards the 10 nm scale. The basis of single electronics is the Coulomb blockade of electron transport which occurs when an electron can be localized on an isolated island. Many structures have been devised to demonstrate the Coulomb blockade and single electron transistors (SETs), based on this effect have been constructed. Metallic structures can be fabricated with vertical and lateral island and tunnel barrier structures in which the Coulomb blockade has been demonstrated at temperatures up to 77 K. Semiconductor single electronics has also been demonstrated with GaAs and silicon based structures. Silicon on insulator has the attractive feature that it may be used for conventional CMOS circuits as well as single electronics in the same chip. Several applications of SETs have been demonstrated such as memories and logic circuits. Memories based on charge storage on nanoislands and operating at room temperature will almost certainly have applications in the future. Nanofabrication for SETs requires advances in lithographic techniques well beyond the current state of the art to the sub 10 nm size scale. Electron beam lithography and scanning probe techniques offer the best prospects for the future although some more esoteric techniques based on atomic particle deposition and colloid chemistry may also offer some benefits.