The Future of Nanoelectronics
New materials like carbon nanotubes will complement, not compete with, conventional silicon devices.
The carbon nanotubes and semiconductor nanowires that became available to scientists in the 1990s captured my imagination and attracted me to the field now called nanoelectronics. For an inorganic materials chemist like me, these newly discovered tiny building blocks were like Tinkertoys that could potentially be used to make all kinds of gadgets and widgets. The desire to build something, to invent new structures out of them, spoke to me as a chemist, and I’ve been fascinated by the possibilities of these new nanomaterials ever since.
Thanks to Moore’s Law, however, the electronic devices produced by the conventional semiconductor process are now also “nanoelectronics.” So what will be the role of new nanoelectronics based on chemically synthesized nanostructures, like carbon nanotubes and nanowires? Thermodynamics dictates that chemically synthesized nanostructures will probably never achieve the uniformity and perfection of electronic devices carved out of silicon crystals using conventional lithography. Rather, the strength of the new nanomaterials is in their chemical diversity and flexibility.
Those of us working on novel nanoelectronics should be trying to do things conventional technology simply cannot do, rather then trying to compete directly with the well-established technology. There are opportunities using physical mechanisms that have not been utilized in solid-state electronics. My research group, for example, is working on nanoscale magnetic semiconducting materials that could enable the demonstration of spintronics, which seeks to exploit the spin properties of electrons in computing devices.
The silicon microelectronics industry has been remarkably conservative, using only a very small fraction of the elements in the periodic table. For a long time, after all, reducing the size of transistors, which was made possible because of advances in the lithographic process, was sufficient to sustain the performance of devices as they were scaled down. But size reduction itself simply cannot deliver the necessary increases in performance anymore. New chemically synthesized nanostructures might be suitable for various advanced functions that are difficult to achieve with more conventional silicon-based materials.
We can imagine a future for hybrid devices, combining the strength of both approaches. In such a scenario, we would use exotic materials for new functions that are needed only at certain places on a very large-scale circuit that is generated by a conventional semiconductor process. Newly synthesized nanostructures can also compete in applications where perfection is not of paramount importance but cheap processing, chemical flexibility, and function are. Electronic biosensors in which carbon nanotubes or nanowires are used to detect specific molecules are certainly one of those promising areas, but there may well be others that we have not imagined yet.
How can we organize these new nanostructures and integrate them into useful systems? This is an enormously challenging problem, and though I have worked on it before, I do not pretend that we have fully addressed it. But now that researchers have the Tinkertoys in hand, we can begin to come up with more creative ideas and strategies to manipulate these building blocks.
Song Jin is an assistant professor of chemistry at the University of Wisconsin-Madison. He is a member of this year’s TR35.