A first in integrated nanowire sensor circuitry

Artist's impression of an integrated light sensor circuit based on nanowire arrays (Javey Group). Click here for more information.

Scientists at the U.S. Department of Energy's Lawrence Berkeley National Laboratory and the University of California at Berkeley have created the world's first all-integrated sensor circuit based on nanowire arrays, combining light sensors and electronics made of different crystalline materials. Their method can be used to reproduce numerous such devices with high uniformity.

Nanostructures made with specific chemical, electronic, and other properties have a number of advantages over the same materials in bulk. For example, a nanowire is an ideal shape for a light detector; being virtually one-dimensional, practically "all surface," a nanowire is not only highly sensitive to light energy, but its electronic response is greatly enhanced as well.

To be practical, however, the photosensors must be integrated with electronics on the same chip. And the materials that make an ideal photosensor are necessarily different from those that make a good transistor.

"Our integration of arrays of nanowires that perform separate functions and are made of heterogeneous substances – and doing this in a way that can be reproduced on a large scale in a controlled way – is a first," says Ali Javey, who led the research team. Javey is a staff scientist in Berkeley Lab's Materials Sciences Division (MSD) and an assistant professor in the Electrical Engineering and Computer Sciences Department at UC Berkeley. He and his colleagues report their work in the August 1 edition of Proceedings of the National Academy of Sciences (PNAS).

Randomly oriented nanowires, on the growth substrate at left, are having a "bad hair day. " But after contact printing, the nanowires on the receiver substrate are highly aligned. (Javey group) Click here for more information.

Printed arrays