What Happened to Post‐CMOS?

The rivals with self‐described revolutionary impact have barely progressed to the single device level and rarely to the level of simple circuits and never to CMOS‐competitive switching speeds. This chapter examines what went wrong and whether there is any path to a true post‐CMOS logic technology. Signal propagation is much less lossy and less dispersive than propagation down wires; however, it is still impractical for shorter distances because of the optical to electrical energy costs of transduction. The capacitance of the surrounding wires and vias can be larger than the intrinsic device capacitance. There have been several technological transformations in the history of information technology, all leading to orders of magnitude improvement over their predecessors. CMOS was successful in spite of the fact that device performance was initially inferior to existing bipolar technology. Four‐terminal isolation is inherent in transduction devices, such as the NEMS relay, the PET and the spin transfer torque/domain wall (STT/DW).