THE TECHNOLOGIES BEHIND THE SUPERIOR PERFORMANCE OF ELFYS PHOTODETECTORS
Nearly ideal photoresponse over a wide spectral range
Our photodetectors (Reference ) 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.
Our technology is protected by patents in the U.S. and elsewhere for ElFys Oy.
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 [1-7] 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°.
 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
 M. Garin, J. Heinonen, L. Werner, T.P. Pasanen, V. Vähänissi, A. Haarahiltunen, M. Juntunen and H. Savin, “Black-silicon ultraviolet photodiodes achieve external quantum efficiency above 130%”, Physical Review Letters, Accepted 28 July (2020)
 T. Tsang, A. Bolotnikov, A. Haarahiltunen, J. Heinonen, Quantum efficiency of black silicon photodiodes at VUV wavelengths, Optics Express 28,13299 (2020)
J. Heinonen, T. P. Pasanen, V. Vähänissi, M. A. Juntunen, Hele Savin, Modeling Field Effect in Black Silicon and Its Impact on Device Performance, IEEE Transactions on Electron Devices, 67 (4), 1645-1652, (2020)
 J. Heinonen, C. Modanese, A. Haarahiltunen, H. Kettunen, M. Rossi, J. Jaatinen, M. A. Juntunen, Results on radiation hardness of black silicon induced junction photodetectors from proton and electron radiation, Nuclear Instruments and Methods in Physics Research Section A: Accelerators, Spectrometers, Detectors and Associated Equipment 977, 164294 (2020)
 J. Heinonen, A. Haarahiltunen, M. Dov Serue, V. Vähänissi, T. P. Pasanen, H. Savin, L. Werner, M. A. Juntunen, High-sensitivity NIR photodiodes using black silicon, Proceedings Volume 11276, Optical Components and Materials XVII; 112760G (2020)
 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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