Design of quantum-dot cellular automata for manufacturability

The CMOS transistor has reached the molecular level due to the continuous miniaturization. With devices that small, problems in manufacturing and functionality appear. Since quantum effects become prevalent, technology that would take advantage of them is desirable. One of the proposed novel technologies is the quantum-dot cellular automaton (QCA) [1, 2]. Its basic building block is a QCA cell (Fig. 1) which consists of four quantum dots and a pair of mobile electrons. Two possible configurations of electrons, which can tunnel between the dots, are interpreted as binary logic values. Simple QCA structures termed tiles were presented: the majority gate, the inverter and the wire, all composed exclusively of QCA cells (Fig. 2). These structures are capable of implementing logic functions and transferring data, thus rendering the QCA useful for computation.