Impact ionization in silicon at low charge-carrier energies

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