The relative success of nanoscale RTD, SET and EQCA devices as replacements for CMOS at the system level

A number of new concepts and devices which might replace CMOS were proposed, but often only device aspects are analysed. However the make or break for each device will be how successful it is at the system level. Here we are dealing with three newly proposed devices, namely Resonant Tunneling Diodes (RTDs), Single Electron Tunneling (SET) devices and electronic Quantum Cellular Automata (EQCAs), and present results for the system performance of three device technologies and CMOS. The comparison is made using a standard digital circuit architecture, namely a memory-adder model. The results show that the RTDs offer speed advantages over CMOS, but improvements in the circuit density are limited. The SET offer good packing densities but slow memory systems, whereas logic applications are still far away. The 'solid state' electronic QCAs will suffer both from effectively low packing density and low operating speeds in comparison to CMOS if conventional designs and a 2D architecture are used.