Observation of intersubband real-space transfer in GaAs/AlAs quantum-well structures due to Γ–X mixing

The Γ2–Xz1 intersubband dynamics in GaAs/AlAs quantum-well structures is investigated by time-resolved infrared pump and probe experiments. In the studied structure, the second Γ level in GaAs is nearly resonant to the first Xz level in AlAs, resulting in elastic Γ–X scattering. A biexponential behavior of ground-state recovery has been found with a time constant in the order of 1 ps for the Γ2–Γ1 relaxation and a time constant of 7 ps (at 10 K), which represents the Xz–Γ2 transfer.

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