Scientists at the National Institute of Standards and Technology have successfully built a functional field effect transistor (FET), the basic building block of computer electronics, out of organic molecules. The advantages of building computer chips out of things other than silicon are numerous, especially within specific fields like medicine. High temperatures during manufacturing and the fact that silicon chips have to be rigid are factors that make standard processors difficult to integrate into certain (pliable?) medical devices.
The essential structure consists of two electrical contacts with a channel of semiconductor between them. The researchers found that by applying a specially tailored pretreatment compound to the contacts before applying the organic semiconductor solution, they could induce the molecules in solution to self-assemble into well-ordered crystals at the contact sites.
These structures grow outwards to join across the FET channel in a way that provides good electrical properties at the FET site, but further away from the treated contacts the molecules dry in a more random, helter-skelter arrangement that has dramatically poorer properties–effectively providing the needed electrical isolation for each device without any additional processing steps. The work is an example of the merging of device structure and function that may enable low cost manufacturing, and an area where organic materials have important advantages.
In addition to its potential as a commercially important manufacturing process, the authors note, this chemically engineered self-ordering of organic semiconductor molecules can be used to create test structures for fundamental studies of charge transport and other important properties of a range of organic electronic systems.
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