Theory of carrier dynamics and time resolved reflectivity in InMnAs/GaSb heterostructures

Abstract

We present detailed theoretical calculations of two color, time-resolved pump-probe differential reflectivity measurements. The experiments modeled were performed on InMnAs/GaSb heterostructures and showed pronounced oscillations in the differential reflectivity as well as a time-dependent background signal. Previously, we showed that the oscillations resulted from generation of coherent acoustic phonon wavepackets in the epilayer and were not associated with the ferromagnetism. Now we take into account not only the oscillations, but also the background signal which arises from photoexcited carrier effects. The two color pump-probe reflectivity experiments are modeled using a Boltzmann equation formalism. We include photogeneration of hot carriers in the InMnAs quantum well by a pump laser and their subsequent cooling and relaxation by emission of confined LO phonons. Recombination of electron-hole pairs via the Schockley-Read carrier trapping mechanism is included in a simple relaxation time approximation. The time resolved differential reflectivity in the heterostructure is obtained by solving Maxwell's equations and compared with experiment. Phase space filling, carrier capture and trapping, band-gap renormalization and induced absorption are all shown to influence the spectra.

arXiv comment14 pages, 10 figures

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• Theory of coherent acoustic phonons in InGaN/GaN multi-quantum wells
• Ultrahigh field electron cyclotron resonance absorption in In${}_{1-x}$Mn${}_x$As films
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• Carrier dynamics and coherent acoustic phonons in nitride heterostructures
• Energy dependent amplitude of Brillouin oscillations in GaP
• Transient Charge and Energy Balance in Graphene Induced by Ultrafast Photoexcitation
• Coherent Phonon Dynamics in Short-Period InAs/GaSb Superlattices