Trapping of free electrons in III-V superlattices

Non-radiative trapping of electrons to deep traps in III-V superlattices is studied. An advancement in the technique of the calculation made it possible to avoid some approximation used in earlier calculation and to obtain a simpler, more precise, and clear results that extend applicability of the theory to narrow band gap materials and superlattices. It is shown that the non-radiative trapping rate in regular Huang-Rhys model has an activation temperature dependence with the activation energy equal to a portion of the phonon energy. The trapping to deep states can be accompanied with emission of phonons of different modes with different frequencies that can significantly reduce the activation energy. I argue that the role of superlattice phonons is relatively small except very low temperature where processes with their participation can have zero activation energy. A specific attention is paid in the paper to a qualitative explanation of every step of the calculation and details of the result. The theoretical results are used for understanding of recently measured temperature dependence of the minority carrier lifetime in InAs/GaSb superlattices.