Hybrid CMOS/Nanoelectronic Circuits: Opportunities and Challenges

This is a concise review of the recent work on devices, circuits and architectures for possible hybrid semiconductor/nanodevice integrated circuits based on nanowire crossbars, with similar, simple, two-terminal devices formed at each crosspoint. Special attention is given to the so-called CMOL variety of the hybrids, in which the crossbar is connected to the underlying CMOS circuit, using an area-distributed, pin-based interface. Recent detailed studies have shown that digital hybrid circuits may extend the Moore's Law progress of integrated circuits for 10 to 15 years. Even more impressive, mixed-signal neuromorphic networks (CrossNets) may provide unparalleled performance for some important information processing tasks, and in future may become the first hardware basis for challenging the mammal cerebral cortex in density, far exceeding it in speed, at manageable power consumption. Recently, the hybrid circuit concept received a strong boost from the experimental demonstrations of reproducible crosspoint devices (latching switches) based on amorphous silicon and metal oxides, and of nanowire crossbars with 15-nm-scale half-pitch. However, CMOL technology still faces several significant challenges, briefly discussed in the last section.