Select your localized edition:

Close ×

More Ways to Connect

Discover one of our 28 local entrepreneurial communities »

Be the first to know as we launch in new countries and markets around the globe.

Interested in bringing MIT Technology Review to your local market?

MIT Technology ReviewMIT Technology Review - logo

 

Now Available: Innovators Under 35 2013 See The 2013 List »

Solomon Assefa, 32

Replacing wires with light in chips

IBM

Credit: Steve Moors

Chips that communicate with pulses of light instead of electrical signals could lead to computers that are more power-efficient than today's best machines and up to 1,000 times as fast. IBM researcher Solomon Assefa has brought this prospect a critical step closer.

Assefa has developed a new way to make a photodetector, a very sensitive device that amplifies optical signals and converts them into electrical signals that can be shuttled around in a microprocessor. Ordinarily, photodetectors are made using a process called chemical vapor deposition. But sticking with this process for chip-to-chip connections would make microprocessor manufacturing prohibitively expensive. Instead, Assefa seeds germanium onto a silicon wafer, and then melts it to achieve the regular crystal structure that makes for a good photodetector material. He has also determined when in the chip manufacturing process the photodetector should be added in order to get the best performance possible without degrading the surrounding electronics.

Assefa can demonstrate the performance of his photodetector in the lab. But before a chip incorporating his creation can be commercialized, he will have to figure out how all the rest of its elements can be integrated efficiently. Making today's integrated circuits requires hundreds of steps and dozens of lithographic masks, the stencils used to pattern features on chips. "We don't want to change any of these processes or it really increases the costs," he says. —Katherine Bourzac

2011 TR35 Winners

Solomon Assefa

Replacing wires with light in chips

Christopher Bettinger (video)

Tailoring polymers for biodegradable implants

Alexandra Boltasseva

Using semiconductors to steer light

Jennifer Dionne (video)

Solar cells that see more light

Dae-Hyeong Kim

Stretchable electronics for medical devices

Fengnian Xia (video)

Replacing silicon with graphene

Advertisement

More Innovators Under 35: