Dynamics of the Intraband Light Absorption in Selectively Doped GaAs/AlGaAs Quantum Wells

L.E. Vorobjeva, V.Yu. Panevina, N.K. Fedosova, D.A. Firsova, V.A. Shalygina, A. Seilmeierb, S.R. Schmidtb, E.A. Zibikb, E. Towec and V.V. Kapaevd aSaint Petersburg State Polytechnic University, St. Petersburg 195251, Russia bInstitute of Physics, University of Bayreuth, Bayreuth 95440, Germany cCarnegie Mellon University, Pittsburgh PA 15213, USA dP.N. Lebedev Physical Institute RAS, Moscow 117924, Russia

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Received: 22 08 2004;

Spectral and temperature dependences of equilibrium and non-equi-intersubband light absorption in the mid-infrared spectral range were studied in selectively doped asymmetrical tunnel-coupled GaAs/AlGaAs quantum wells. The temporal evolution of the absorption studied by means of a picosecond pump-probe technique was found to have a biexponential character. The fast decay times are determined by intersubband electron relaxation due to electron scattering by optical phonons and impurities. The presence of long decay times in transient mid-infrared absorption is probably connected with electron transitions from the states in barrier (X and L valleys as well as deep centers) to the states of the quantum well. Experimentally determined intersubband scattering times are compared with the calculated ones.

DOI: 10.12693/APhysPolA.107.429 PACS numbers:42.55.Px, 42.60.-v