Impurity improves nanolasers efficiency

Impurity improves nanolasers efficiency

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 Scientists at Australian National University have made a discovery which will be central to the develop­ment of low-cost biomedical sensors, quantum computing as well as a fast­er internet. Researcher Tim Burgess added atoms of zinc as impurities 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.

The impurities led to a 100 times improvement in the amount of light 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, a PhD student in the ANU Research School of Physics and Engineering.

Gallium arsenide is a common material used in photovoltaic cells, lasers and light-emitting diodes (LEDs), but is challenging to work with at the nanoscale as the mate­rial requires a surface coating be­fore it will produce light. The new result complements these suc­cesses by increasing the amount of light generated inside the nano­structure, said research group leader Professor Chennupati Jagadish, from the ANU Research School of Physics Sciences.

Burgess said that the addition of the impurity to gallium arsenide, a process called doping, did more than just improve the light emission. “The doped gallium arsenide has a very short carrier lifetime of only a few pi­coseconds, which meant it would be well suited to use in high speed elec­tronics components,” he added.