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Engineers Enable 'Bulk' Silicon to Emit Visible Light for the First Time



March 27, 2013 – Comments (2)

Extremely cool development to support the future of high-speed computing.


Engineers Enable 'Bulk' Silicon to Emit Visible Light for the First Time
Mar. 27, 2013

Electronic computing speeds are brushing up against limits imposed by the laws of physics. Photonic computing, where photons replace comparatively slow electrons in representing information, could surpass those limitations, but the components of such computers require semiconductors that can emit light.

Now, research from the University of Pennsylvania has enabled "bulk" silicon to emit broad-spectrum, visible light for the first time, opening the possibility of using the element in devices that have both electronic and photonic components.

The research was conducted by associate professor Ritesh Agarwal, postdoctoral fellow Chang-Hee Cho and graduate students Carlos O. Aspetti and Joohee Park, all of the Department of Materials Science and Engineering in Penn's School of Engineering and Applied Science.

Their work was published in Nature Photonics.

Certain semiconductors, when imparted with energy, in turn emit light; they directly produce photons, instead of producing heat. This phenomenon is commonplace and used in light-emitting diodes, or LEDs, which are ubiquitous in traffic signals, new types of light bulbs, computer displays and other electronic and optoelectronic devices. Getting the desired photonic properties often means finding the right semiconducting material. Agarwal's group produced the first ever all-optical switch out of cadmium sulfide nanowires, for example.

Semiconducting materials -- especially silicon -- form the backbone of modern electronics and computing, but, unfortunately, silicon is an especially poor emitter of light. It belongs to a group of semiconducting materials, which turns added energy into heat. This makes integrating electronic and photonic circuits a challenge; materials with desirable photonic properties, such as cadmium sulfide, tend to have poor electrical properties and vice versa and are not compatible with silicon-based electronic devices.

"The problem is that electronic devices are made of silicon and photonic devices are typically not," Agarwal said. "Silicon doesn't emit light and the materials that do aren't necessarily the best materials for making electronic devices."

With silicon entrenched as the material of choice for the electronics industry, augmenting its optical properties so it could be integrated into photonic circuitry would make consumer-level applications of the technology more feasible.

2 Comments – Post Your Own

#1) On March 27, 2013 at 5:11 PM, ChrisGraley (30.25) wrote:

Add quantum dots to the equation and suddenly cell phone displays get fantastic resolution and use less power for a much cheaper price. Same for televisions and quite possibly pico projectors.

Lots of uses for this technology. 

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#2) On March 28, 2013 at 10:00 AM, binve (< 20) wrote:


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