Models and designs of clocked molecular quantum-dot cellular automata circuits.

Quantum-dot cellular automata (QCA) is a general-purpose, low-energy, high-efficiency, general purpose computing paradigm. QCA computation may overcome challenges such as heat dissipation and the clock speed bottleneck facing the extreme scaling of CMOS. A molecular implementation of QCA promises nanometer-scale device sizes, ultra high device densities, and ∼THz clock speed all at room temperature. We model and design molecular QCA circuits immersed in applied electric fields to address various technical challenges in the path to realizing molecular QCA. We explore the use of molecular QCA circuits and field-generating electrodes for both the write-in and read-out of classical bits, two problems central to interfacing conventional semiconductor logic with molecular QCA logic. We design and model novel circuits which may support the input and output of classical bits with the help of an applied electric field. While electric fields are useful for input and output circuits, they may disrupt information-processing circuits. Therefore, we also explore the extent to which molecular circuits (logic and interconnects) tolerate applied electric fields. We demonstrate that molecular QCA circuits can tolerate significant unwanted electric fields, well beyond those fields required for bit input or output.