Nanolasers grown on silicon surface

Nanolasers now can be grown directly onto a silicon surface, an achievement that could lead to a new class of faster, more efficient microprocessors, as well as to powerful biochemical sensors that use optoelectronic chips.

The results are expected to affect a number of scientific fields, including materials science, transistor technology, laser science, optoelectronics and optical physics, according to a group of engineers at the University of California. Their work was published online Feb. 6, 2011, in Nature Photonics (doi: 10.1038/nphoton.2010.315).

In search of a better way to harness light particles so that they may carry more data than electrical signals can, the researchers turned to a class of materials known as III-V semiconductors to create light-based components such as LEDs and lasers. Silicon, the foundation material for most modern electronics, is deficient at generating light.

They found that marrying III-V with silicon to create a single optoelectronic chip is problematic. Although it can be done, the material can get damaged in the process because the growth of the semiconductors traditionally has involved high temperatures of more than 700 °C.

The researchers found a way to grow nanopillars made of indium gallium arsenide, a III-V material, onto a silicon surface at a relatively cooler temperature of 400 °C. They used metallorganic chemical vapor deposition to grow the nanopillars on the silicon. The technique has the potential to be mass manufactured since systems used to make thin-film solar cells and LEDs are already commercially available.

“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 Roger Chen, University of California, Berkeley, graduate student in electrical engineering and computer sciences.

Shown are a schematic (left) and various scanning electron microscope images of nanolasers grown directly on a silicon surface. The achievement could lead to a new class of optoelectronic chips. Courtesy of Connie Chang-Hasnain Group, UC Berkeley.

With the ability to generate near-IR laser light, the nanopillar can be packed into small spaces while consuming very little energy. Growing nanolasers directly onto silicon could lead to highly efficient silicon photonics. In addition, the technique may provide a new avenue for engineering on-chip nanophotonic devices, including lasers, photodetectors, modulators and solar cells, Chen said.

The research was supported by DARPA and a US Department of Defense National Security Science and Engineering Faculty fellowship.