THE TECHNOLOGIES BEHIND THE SUPERIOR PERFORMANCE OF ELFYS PHOTODETECTORS

Nearly ideal photoresponse over a wide spectral range

Our photodetectors (Reference [1]) have a nearly ideal photoresponse from 200 nm to 950 nm, with 96% external quantum efficiency (certified by PTB, The National Metrology Institute of Germany). The collection efficiency is enhanced by employing a surface nanostructuring technique combined with an atomic layer deposited coating.

The certified photoresponse curve and comparison to typical pn-junction silicon photodiodes is shown on the side. Ideal photoresponse corresponding to 100% EQE is also shown for reference.

 

Exceptional photoresponse in the ultraviolet (2 times higher)

The applied highly effective surface passivation technology eliminates surface recombination. In combination with the suppression of the dead layer, it significantly boosts the collection efficiency of signal charges generated really close to the photodiode top surface, yielding an exceptional over 100% quantum efficiency for ultraviolet light. See also References [2] and [3] or contact us for further details.

The photoresponse is 2 times higher than other state-of-the art technologies at 240 nm, as seen by the certified photoresponse in ultraviolet region and its comparison to typical pn-junction silicon photodiodes shown on the side. The ideal photoresponse corresponding to 100% EQE is also shown for reference.

 

Ultra-wide sensing angle with extremely high absorbance (> 95% @ 60°)

The black silicon surface, combined with a tailored atomic layer deposited coating layer, greatly enhances the surface absorbance for an extended range of sensing angles, with single-digit reflectance up to 1000 nm and 60° incident angle.

The measured angle-dependent surface reflectance of our photodetectors is shown on the side, for sensing angles from 10° to 70°.

References

[1] M. A. Juntunen, J. Heinonen, V. Vähänissi, P. Repo, D. Valluru, and H. Savin, “Near-unity quantum efficiency of broadband black silicon photodiodes with an induced junction”. Nature Photonics, 10(12), 777-781, 2016

[2] M. Garin, J. Heinonen, L. Werner, T.P. Pasanen, V. Vähänissi, A. Haarahiltunen, M. Juntunen and H. Savin, ”Black Silicon UV photodiodes achieve >130% external quantum efficiency”. (Submitted on 31.07.2019)

[3] M. A. Juntunen, J. Heinonen, H. S. Laine, V. Vähänissi, P. Repo, A. Vaskuri and H. Savin, ”N-type Induced junction Black Silicon photodiode for UV detection”. Proc. SPIE 10249, Integrated Photonics: Materials, Devices, and Applications IV, 102490I, 2017

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