Fundamental Limits to Individual Devices

Communications and computing rely ultimately on individual devices such as transistors, optical switching elements, memory elements, and detectors of electrical, optical, and radio signals. These devices are linked into physical modules like integrated circuits that perform the necessary functions or computations needed for the communications network or computer. For the last two decades, the trends of technology have dramatically decreased the size and power requirements of individual elements so that they can be integrated into a single complex package, thus reducing parts needed, space, and cost of functional modules such as communications receivers. I expect that these trends will continue, using what we have learned from nanotechnology research, until either fundamental physical limits to the individual devices are reached, or which is more likely, until we hit a new bottleneck of how to design and achieve the interconnection of these devices. When devices approach the nanometer scale, they will no longer be identical but will have a statistical distribution of characteristics: for example, in a 10 nm channel length transistor, the number of dopant atoms will be in the tens or hundreds and vary from transistor to transistor produced in an identical way, due to the random nature of the dopant diffusion process. This means that there will necessarily be a statistical variation of turn-on voltages, break-down voltages, channel conductivity, and so forth.

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