Bis-Ferrocene Molecular QCA Wire: Ab Initio Simulations of Fabrication Driven Fault Tolerance

Molecular quantum dot cellular automata (MQCA) are among the most promising emerging technologies for the expected theoretical operating frequencies (THz), the high device densities, and the noncryogenic working temperature. Due to the small size of an MQCA cell, based on one or two molecules, the device prototyping and even a simple circuit fabrication are limited by the lack of control on the technological process. In this paper, we performed an analysis of the possible fabrication defects of a molecular QCA wire built with ad hoc synthesized bis-ferrocene molecules. We evaluated the fault tolerance of a real QCA device and assessed its performance in nonideal conditions due to the fabrication criticalities as we faced in our experiments. We achieved these results by defining a new methodology for the fault analysis in the MQCA technology, based both on ab initio simulations and theoretical computations. The obtained results give quantitative information on the safe operating area (SOA) of a bis-ferrocene molecular wire, and represented an important feedback to improve the technological process for the final experimental set-up.