In Nanolasers, A Little Impurity Goes A Long Way

By adding impurities in the form of zinc atoms, researchers have improved nanolaser light emission by a hundredfold.

AsianScientist (Jul. 14, 2016) – In somewhat of a happy accident, scientists at the Australian National University (ANU) have improved the performance of tiny lasers by adding impurities. This discovery could someday lead to the development of low-cost biomedical sensors, quantum computing and faster internet.

PhD student Mr. Tim Burgess from the ANU Research School of Physics and Engineering added atoms of zinc to lasers one hundredth the diameter of a human hair and made of gallium arsenide, a material used extensively in smartphones and other electronic devices. These impurities led to a hundredfold increase in the amount of light emitted from the lasers.

“Normally you wouldn’t even bother looking for light from nanocrystals of gallium arsenide—we were initially adding zinc simply to improve the electrical conductivity,” said Burgess, the first author of the study.

“It was only when I happened to check for light emission that I realized we were onto something.”

Gallium arsenide is a common material used in smartphones, photovoltaic cells, lasers and light-emitting diodes, but is challenging to work with at the nanoscale as the material requires a surface coating before it will produce light.

“It is an exciting discovery and opens up opportunities to study other nanostructures with enhanced light emission efficiency so that we can shrink the size of the lasers further,” said research group leader Professor Chennupati Jagadish from the ANU Research School of Physics Sciences.

Burgess noted that the addition of the impurity to gallium arsenide, in a process called doping, has improved more than the light emission.

“The doped gallium arsenide has a very short carrier lifetime of only a few picoseconds, which means it would be well-suited for use in high speed electronics components. The doping has really has given these nanolasers a performance edge.”

The research is published in Nature Communications.

The article can be found at: Burgess et al. (2016) Doping-Enhanced Radiative Efficiency Enables Lasing in Unpassivated GaAs Nanowires.


Source: Australian National University.
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