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HL: Fachverband Halbleiterphysik
HL 59: THz and MIR physics in semiconductors
HL 59.1: Vortrag
Donnerstag, 19. März 2020, 09:30–09:45, POT 151
Light impact ionization in HgTe quantum wells close to critical thickness — •Stefan Hubmann1, Grigory Budkin2, Michael Urban1, Vasily Bel’kov2, Eugenius Ivchenko2, Alexander Dmitriev2, Johannes Ziegler1, Dimitriy Kozlov3, Nikolay Mikhailov3, Sergey Dvoretsky3, Ze-Don Kvon3, Dieter Weiss1, and Sergey Ganichev1 — 1Terahertz Center, University of Regensburg, 93040 Regensburg, Germany — 2Ioffe Institute, 194021 St. Petersburg, Russia — 3Rzhanov Institute of Semiconductor Physics, 630090 Novosibirsk, Russia
We report on the observation of terahertz radiation induced band-to-band impact ionization in HgTe quantum well structures close to critical thickness characterized by a nearly linear energy dispersion. This carrier multiplication process is detected for frequencies from 0.6 to 1.07 THz and in a temperature range from 4 to 90 K. Furthermore, the product of the angular radiation frequency ω and the momentum relaxation time τ is close to unity denoting a transition between the quasi-static regime ωτ≪1 and the high-frequency regime ωτ≫1. We developed a microscopic theory of light impact ionization for both regimes in HgTe quantum wells with nearly linear energy dispersion. We show that the probability of impact ionization in the transition regime is proportional to exp(−E02/E2), of the radiation electric field amplitude E and the characteristic field parameter E0, where E0 is strongly dependent on the radiation frequency.