Modeling QCA defects at molecular-level in combinational circuits

This paper analyzes the deposition defects in devices and circuits made of quantum-dot cellular automata (QCA) for molecular implementation. Differently from metal-based QCA, in this type of implementation a defect may occur due to the erroneous deposition of cells (made of molecules) on a substrate, i.e. no cell, or an additional cell is placed either near, or within the layout configuration of a QCA device. The effects of an erroneous cell deposition defect are analyzed by considering the induced functional faults for different QCA devices, such as the majority voter, the inverter and various wire configurations (straight, L-shape, coplanar crossing and fanout). Extensive simulation results are provided. As an example, testing of an EXOR circuit is analyzed in detail.