Clocking of molecular quantum-dot cellular automata

Quantum-dot cellular automata (QCA) may provide a novel way to bypass the t ransistor paradigm to form ultrasmall computing elements. In the QCA paradi gm information is represented in the charge configuration of a QCA cell, wh ich maps naturally to a binary model. Molecular QCA implementations are bei ng explored where the quantum dots in the cell take the form of redox cente rs in a molecule. Clocking has proved important in QCA cells synthesized so far. Here we examine a method to clock molecular QCA cells which are assem bled at an interface. The clocking signals in this scheme originate from wi res buried below the QCA surface. We present a simplified model of this clo cking method and examine its behavior as a molecular shift register. (C) 20 01 American Vacuum Society.