Authors: M. Mitic, M.C. Cassidy, K.D. Petersson, E. Gauja, R.P. Starrett, R. Brenner, C. Yang, D.N. Jamieson, R.G. Clark and A.S. Dzurak
Affilation: University of New South Wales, Australia
Pages: 9 - 12
Keywords: quantum cellular automata, Si, MOS technology, single-electron transistor, phosphorous implantation
Quantum-dot cellular automata (QCA)  represent a potential paradigm shift in computation, offering elegant solutions to the critical problems of device density, interconnection and power dissipation. To date QCA cells have been experimentally demonstrated in Al systems  and magnetic dot systems , with promising results also in GaAs quantum dot systems . Here we report the experimental demonstration  of a basic QCA cell in a phosphorus-doped silicon system. Si-based systems offer advantages including compatibility with scalable Si-MOS technologies, together with great potential for effective cell size reduction, possibly leading to room-temperature operation of single donor Si-based QCA .The QCA device studied here consisted of two pairs of metallic dots, separated from source and drain reservoirs by tunnel barriers. The metallic regions were formed by low-energy (14 keV) phosphorous ion implantation through a nanoscale mask defined using electron beam lithography. Metallic gates used to control the electrostatic potential of the dots, along with Al-Al2O3 single-electron transistors used for QCA cell state-readout, were fabricated on the surface of this structure, isolated from the dots and reservoirs by a 5nm layer of SiO2. The device was operated in a dilution refrigerator at a base temperature of 50mK. QCA operation was demonstrated by the switching of a single electron between output dots, controlled by a single electron switching in the input (driver) dots. Results of the measurements are in excellent agreement with modelling .