Towards the design of hybrid QCA tiles targeting high fault tolerance

The increasing fabrication cost of CMOS-based computing devices and the ever-approaching limits of their fabrication have led to the search for feasible options with high device density and low power waste. Quantum-dot cellular automata (QCA) is an emerging technology with such potential to match the design target beyond the limits of state-of-the-art CMOS. But nanotechnologies, like QCA are extremely susceptible to various forms of flaws and variations during fabrication at nano scale. Thus, the exploration of ingenious fault tolerant structure around QCA is gaining high importance. This work targets a new robust QCA tile structure hybridizing rotated and non-rotated cell together resulting lesser kink energy. Different QCA logic primitives (majority/minority logic, fanout tiles, etc.) are made using such hybrid cell structure. The functional characterization using the kink energy and the polarization level of such QCA structures under different cell defects have been thoroughly investigated. The results suggest that the proposed QCA logic primitives have achieved high fault tolerance of 97.43 %. Also, 100 % fault tolerance can be ascertained if the proposed logic circuit drives the correct output with the application of \(\langle \)001, 011\(\rangle \) as a primitive test vector only. A comparative performance of the proposed logic over existing structure makes it more reliable.