Impact ionization in silicon at low charge-carrier energies

Mikhail Korpusenko (Corresponding Author), Anna Vaskuri, Farshid Manoocheri, Erkki Ikonen

Research output: Contribution to journalArticleScientificpeer-review

2 Citations (Scopus)


Photons absorbed in silicon produce electron-hole pairs, which can cause impact ionization and quantum yield larger than one. Reliable determination of quantum yield at low charge-carrier energies (<4 eV) has been challenging because photon losses due to reflectance and charge-carrier losses due to recombination affect the resulting photocurrent. Here, we present how the measurement of this fundamental characteristic of silicon crystals can be improved in the charge-carrier energy range of 1.6-4 eV by using a predictable quantum efficient detector based on induced junction photodiodes optimized for photon-to-electron conversion efficiency. The measured quantum yield values are compared with the results of theoretical calculations, revealing increased impact-ionization probabilities at 2.25 and 3.23 eV on the top of a smooth background curve calculated by a model based on free charge carriers in the silicon lattice. For the results at the lowest energies, both data and an asymptotic extrapolation model suggest that quantum yield exceeds unity by ∼10−4 at 1.6 eV corresponding to a photon wavelength of 450 nm.

Original languageEnglish
Article number085119
JournalAIP Advances
Issue number8
Publication statusPublished - 1 Aug 2023
MoE publication typeA1 Journal article-refereed


We would like to thank Lutz Werner and Ulrike Linke for useful discussions on quantum yield and the related measurement results. Projects chipS⋅CALe (Contract No. 18SIB10) and S-CALeUp (Contract No. 22IEM06) leading to this publication have received funding from the EMPIR Program and from the European Partnership on Metrology, respectively, co-financed by the participating states and the European Union’s Horizon 2020 and Horizon Europe Research and Innovation programs. This work was also supported by the Academy of Finland Flagship Program, Photonics Research and Innovation (PREIN), Decision No. 320167.


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