DOI 10.1007s10836-006-0627-8 Reliability and Defect Tolerance in Metallic Quantum-dot Cellu.pdf

JOURNAL OF ELECTRONIC TESTING: Theory and Applications, 2007 * 2007 Springer Science + Business Media, LLC. Manufactured in The United States. DOI: 10.1007/s10836-006-0627-8 Reliability and Defect Tolerance in Metallic Quantum-dot Cellular Automata MO LIU AND CRAIG S. LENT Department of Electrical Engineering, University of Notre Dame, Notre Dame, IN 46556, USA lent@nd.edu Received March 2, 2006; Revised October 17, 2006 Editor: M. Tehranipoor Abstract. The computational paradigm known as quantum-dot cellular automata (QCA) encodes binary information in the charge configuration of Coulomb-coupled quantum-dot cells. Functioning QCA devices made of metal-dot cells have been fabricated and measured. We focus here on the issue of robustness in the presence of disorder and thermal fluctuations. We examine the performance of a semi-infinite QCA shift register as a function of both clock period and temperature. The existence of power gain in QCA cells acts to restore signal levels even in situations where high speed operation and high temperature operation threaten signal stability. Random variations in capacitance values can also be tolerated. Keywords: QCA, molecular electronics, single electronics, quantum-dot cellular automata, nanoelectronics 1. Introduction Conventional transistor-based CMOS technology faces great challenges with the down-scaling of device sizes in recent years. Issues such as quantum effects, dopant- induced disorder, and power dissipation may hinder further progress in scaling microelectronics. As the scaling approaches a molecular level, a new paradigm beyond using current switches to encode binary informa- tion may be needed. Quantum-dot cellular automata (QCA) [1–3, 6, 12, 13, 18, 21] emerges as one such a paradigm. In the QCA approach bit information is encoded in the charge configuration within a cell. Columbic interaction between cells is sufficient to accomplish the computation; no current flows out of the cell. It has been shown that very l