Characterisation, applicability and defect analysis for tiles nanostructure of quantum dot cellular automata

Quantum dot cellular automata (QCA) is an emerging technology for nanoscale computing. In this paper, our contribution is to enhance the applicability of 3 x 3 tile nanostructure in QCA. We introduced few novel 3 x 3 active-type tiles, namely triple fan-output tiles or butterfly tile, five-input majority voter (MV) and fault-tolerant 3 x 3 tile-coupled majority-minority voter. We also explored the cascading effect on 3 x 3 tile. Triple fan-out tile is applicable to drive three outputs simultaneously. Five-input MV, which is another active-type tile we proposed, is applicable for designing five-variable or five addressing, advanced computations. In passive-type 3 x 3 tiles, we introduce symmetrical baseline tiles and asymmetrical fully populated fan-in tiles. QCA design was found to be having high error during fabrication of device. We made exhaustive simulation for analysing the defect that can occur during fabrication process. Defects such as extra cell deposition, missing cell deposition and displaced cell deposition for QCA are prone to occur. Fault analyses of the above-mentioned 3 x 3 tiles are performed. We also focused on the effect of extra dot or missing dot deposition, during the chemical synthesis phase.