February 12, 2016

Silicon chip with integrated laser: Light from a nanowire

Benedikt Mayer und Lisa Janker an der Epitaxieanlage im Walter Schottky Institut
der TU München – Foto: Uli Benz / TUM

(February 12, 2016)  Nanolaser for information technology

Physicists at the Technical University of Munich (TUM) have developed a nanolaser, a thousand times thinner than a human hair. Thanks to an ingenious process, the nanowire lasers grow right on a silicon chip, making it possible to produce high-performance photonic components cost-effectively. This will pave the way for fast and efficient data processing with light in the future.

Ever smaller, ever faster, ever cheaper – since the start of the computer age the performance of processors has doubled on average every 18 months. 50 years ago already, Intel co-founder Gordon E. Moore prognosticated this astonishing growth in performance. And Moore’s law seems to hold true to this day.

But the miniaturization of electronics is now reaching its physical limits. “Today already, transistors are merely a few nanometers in size. Further reductions are horrendously expensive,” says

Professor Jonathan Finley, Director of the Walter Schottky Institute at TUM. “Improving performance is achievable only by replacing electrons with photons, i.e. particles of light.”

Nanodrähte aus Gallium-Arsenid auf einer Silizium-Oberfläche - Bild: G. Kolblmüller / TUM

Photonics – the silver bullet of miniaturization

Data transmission and processing with light has the potential of breaking the barriers of current electronics. In fact, the first silicon-based photonics chips already exist. However, the sources of light for the transmission of data must be attached to the silicon in complicated and elaborate manufacturing processes. Researchers around the world are thus searching for alternative approaches.

Scientists at the TU Munich have now succeeded in this endeavor: Dr. Gregor Koblmüller at the Department of Semiconductor Quantum-Nanosystems has, in collaboration with Jonathan Finley, developed a process to deposit nanolasers directly onto silicon chips. A patent for the technology is pending.

Growing a III-V semiconductor onto silicon requires tenacious experimentation. “The two materials have different lattice parameters and different coefficients of thermal expansion. This leads to strain,” explains Koblmüller. “For example, conventional planar growth of gallium arsenide onto a silicon surface results therefore in a large number of defects.”

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