Impact ionization of excitons in single-crystal silicon and its effect on the exciton concentration and luminescence near the fundamental absorption edge
Abstract:
The effect of impact ionization of excitons by free charge carriers on the exciton concentration in single-crystal silicon ($c$-Si) at room temperature and at a high injection level is investigated. At sufficiently high concentrations of free electrons $(n)$, the impact ionization dominates over thermal ionization. At such n, the effect results in much lower exciton concentrations $n_{\mathrm{ex}}(n)$ compared to those with disregard of it and linear or almost linear portions in the dependences $n_{\mathrm{ex}}(n)$ and the dependences of the near-band-edge luminescence intensity in $c$-Si on the intensity of its excitation. The proposed technique for calculating $n_{\mathrm{ex}}$ can be developed for other semiconductors at other temperatures.
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