AVS 56th International Symposium & Exhibition
    Nanometer-scale Science and Technology Wednesday Sessions
       Session NS-WeM

Paper NS-WeM11
Control of Coupled Silicon Atomic Quantum Dots for Nano-Electronic Computing Architectures

Wednesday, November 11, 2009, 11:20 am, Room L

Session: Nanoscale Devices and Sensors and Welch Award
Presenter: J. Pitters, National Institute for Nanotechnology, Canada
Authors: J. Pitters, National Institute for Nanotechnology, Canada
B. Haider, University of Alberta, Canada
G. Dilabio, National Institute for Nanotechnology, Canada
L. Livadaru, University of Alberta, Canada
J. Mutus, University of Alberta, Canada
R. Wolkow, University of Alberta, Canada
Correspondent: Click to Email
Coupled quantum dots form an attractive basis both for fundamental studies of single electron control and as potential building blocks for future nano-electronic devices. One computing scheme, Quantum-dot Cellular Automata (QCA), is based upon “cells” of tunnel coupled quantum dots and electrostatic interactions between adjacent cells to transmit binary information and perform calculations with minuscule power consumption. Efforts to fabricate electrostatic QCA devices have been limited by the need for extreme cryogenic conditions. We have demonstrated a new approach using the scanning tunneling microscope (STM) at room temperature. We show that the silicon atom dangling bond (DB) state, on an otherwise hydrogen terminated surface, serves as a quantum dot. These atomic quantum dots can be assembled into multi-DB ensembles through precise hydrogen atom removal using the STM tip. Assembly at critical distances leads to electron tunnel coupling between DBs and control over the net electron occupation of assembled quantum dot DBs is also demonstrated. Additionally, it is shown that a pair of tunnel-coupled DBs can be switched, using electrostatic control, from a symmetric bi-stable state to one exhibiting an asymmetric electron occupation. Similarly, the setting of an antipodal state in a square assembly of four DBs is achieved, demonstrating at room temperature the essential building block of a quantum cellular automata device.