Growing nanolasers on silicon paves way for on-chip photonics

Monday, February 7, 2011

LONDON - Engineers at the University of California, Berkeley, have developed a way to grow nanolasers directly onto a silicon surface paving way to faster, more efficient microprocessors in the future.

The finding may also lead to powerful biochemical sensors that use optoelectronic chips.

“Our results impact a broad spectrum of scientific fields, including materials science, transistor technology, laser science, optoelectronics and optical physics,” said the study’s principal investigator, Connie Chang-Hasnain.

Silicon, that forms the foundation of modern electronics, is extremely deficient at generating light, so engineers have turned to another class of materials known as III-V semiconductors to create light-based components such as light-emitting diodes (LEDs) and lasers.

But the researchers pointed out that marrying III-V with silicon to create a single optoelectronic chip has been problematic.

The UC Berkeley researchers overcame this limitation by finding a way to grow nanopillars made of indium gallium arsenide, a III-V material, onto a silicon surface at the relatively cool temperature of 400 degrees Celsius.

“Working at nanoscale levels has enabled us to grow high quality III-V materials at low temperatures such that silicon electronics can retain their functionality,” said Chen.

The researchers used metal-organic chemical vapor deposition to grow the nanopillars on the silicon.

“This technique is potentially mass manufacturable, since such a system is already used commercially to make thin film solar cells and light emitting diodes,” said Chang-Hasnain.

Once the nanopillar was made, the researchers showed that it could generate near infrared laser light at room temperature. The hexagonal geometry dictated by the crystal structure of the nanopillars creates a new, efficient, light-trapping optical cavity. Light circulates up and down the structure in a helical fashion and amplifies via this optical feedback mechanism.

The unique approach of growing nanolasers directly onto silicon could lead to highly efficient silicon photonics, said the researchers. They noted that the miniscule dimensions of the nanopillars-smaller than one wavelength on each side, in some cases-make it possible to pack them into small spaces with the added benefit of consuming very little energy.

“Ultimately, this technique may provide a powerful and new avenue for engineering on-chip nanophotonic devices such as lasers, photodetectors, modulators and solar cells,” said Chen.

The findings have been published in the journal Nature Photonics. (ANI)

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