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arXiv · 2001.10263

Impact ionization induced by terahertz radiation in HgTe quantum wells of critical thickness

S. Hubmann·G. V. Budkin·M. Urban·V. V. Bel'kov·A. P. ~Dmitriev·J. Ziegler·D. A. Kozlov·N. N. Mikhailov·S. A. Dvoretsky·Z. D. Kvon·D. Weiss·S. D. Ganichev
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Abstract

We report on the observation of terahertz (THz) radiation induced band-to-band impact ionization in \HgTe quantum well (QW) structures of critical thickness, which are characterized by a nearly linear energy dispersion. The THz electric field drives the carriers initializing electron-hole pair generation. The carrier multiplication is observed for photon energies less than the energy gap under the condition that the product of the radiation angular frequency $\omega$ and momentum relaxation time $\tau_{\text l}$ larger than unity. In this case, the charge carriers acquire high energies solely because of collisions in the presence of a high-frequency electric field. The developed microscopic theory shows that the probability of the light impact ionization is proportional to $\exp(-E_0^2/E^2)$, with the radiation electric field amplitude $E$ and the characteristic field parameter $E_0$. As observed in experiment, it exhibits a strong frequency dependence for $\omega \tau \gg 1$ characterized by the characteristic field $E_0$ linearly increasing with the radiation frequency $\omega$.

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S. Hubmann, G. V. Budkin, M. Urban, V. V. Bel'kov, A. P. ~Dmitriev, J. Ziegler, D. A. Kozlov, N. N. Mikhailov, S. A. Dvoretsky, Z. D. Kvon, D. Weiss, S. D. Ganichev. 2020-01-28. Impact ionization induced by terahertz radiation in HgTe quantum wells of critical thickness. https://doi.org/10.1007/s10762-020-00690-6

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