Black Silicon Photodetector Breaks the 100% Efficiency Limit, Shocking Scientists

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UV-Light Triggers Electron Multiplication in Nanostructures

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UV-light triggers electron reproduction in nanostructures. Credit: Wisa Förbom

The performance was so high that in the beginning the scientists had a tough time thinking the outcome. Now Aalto University spin-off business ElFys Inc. currently provides the record detectors for numerous market sectors.

Aalto University scientists have actually established a black silicon photodetector that has actually reached above 130% performance. Thus, for the very first time, a single photovoltaic gadget has actually surpassed the 100% external quantum performance limitation at UV. This result opens brand-new opportunities for enhancing performances beyond the popular Shockley-Queisser limitation.

“When we saw the results, we could hardly believe our eyes. Straight away we wanted to verify the results by independent measurements,” states Prof. Hele Savin, head of the Electron Physics research study group at Aalto University.  

The independent measurements were performed by the German National Metrology Institute, Physikalisch-Technische Bundesanstalt (PTB), which is understood to offer the most precise and dependable measurement services in Europe.

Head of the PTB Laboratory of Detector Radiometry, Dr. Lutz Werner remarks, “After seeing the results, I instantly realized that this is a significant breakthrough — and at the same time, a much-welcomed step forward for us metrologists dreaming of higher sensitivities.”

The trick behind the development: Unique nanostructures

The external quantum performance of a gadget is 100% when one inbound photon creates one electron to the external circuit. 130% performance implies that a person inbound photon creates around 1.3 electrons.

The scientists learnt that the origin of the incredibly high external quantum performance depends on the charge-carrier reproduction procedure inside silicon nanostructures that is activated by high-energy photons. The phenomenon has actually not been observed previously in real gadgets given that the existence of electrical and optical losses has actually lowered the variety of gathered electrons. 

“We can collect all multiplicated charge carriers without a need for separate external biasing as our nanostructured device is free of recombination and reflection losses,” Prof. Savin describes.  

In practice, the record performance implies that the efficiency of any gadget that is making use of light detection can be considerably enhanced. Light detection is currently utilized extensively in our daily life, for instance, in automobiles, smart phones, smartwatches, and medical gadgets.

“Our detectors are gaining a lot of attraction at the moment, especially in biotechnology and industrial process monitoring,” states Dr. Mikko Juntunen, CEO of Aalto University spin-off business, Elfys Inc. They are currently making the record detectors for industrial usage.

The results causing the record performance have actually been accepted for publication in Physical Review Letters with the title “Black-silicon ultraviolet photodiodes achieve external quantum efficiency above 130%.”

Reference: “Black-Silicon Ultraviolet Photodiodes Achieve External Quantum Efficiency above 130%” by M. Garin, J. Heinonen, L. Werner, T. P. Pasanen, V. Vähänissi, A. Haarahiltunen, M. A. Juntunen and H. Savin, 8 September 2020, Physical Review Letters.
DOI: 10.1103/PhysRevLett.125.117702



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