Molecular QCA design with chemically reasonable constraints

In this article we examine the impacts of the fundamental constraints required for circuits and systems made from molecular Quantum-dot Cellular Automata (QCA) devices. Our design constraints are “chemically reasonable” in that we consider the characteristics and dimensions of devices and scaffoldings that have actually been fabricated. This work is a necessary first step for any work in QCA CAD, and can also help shape experiments in the physical sciences for emerging, nano-scale devices. Our work shows that QCA circuits, scaffoldings, substrates, and devices should all be considered simultaneously. Otherwise, there is a very real possibility that the devices and scaffoldings that are eventually manufactured will result in devices that only work in isolation. “Chemically reasonable” also means that expected manufacturing defects must be considered. In our simulations we introduce defects associated with self-assembled systems into various designs to begin to define manufacturing tolerances. This work is especially timely as experimentalists are beginning to work on merging experimental tracks that address devices and scaffolds—and the end result should facilitate correct logical operations.