Carrier capture and relaxation in charged quantum dots triggered by vibrational relaxation

Abstract

Local polarization and the strain of the crystal lattice around the charged quantum dot in semiconductors must vibrate to relax when the mobile carrier is captured by the dot and makes it uncharged. Triggered vibrations induce the sudden perturbation of electronic states in the quantum dot. The Hamiltonian of electron interaction with a local vibrating field and carrier capture time are calculated. It is shown that the principle of uncertainty has a strong influence on this effect. The calculated values of electron capture time are on a sub-picosecond timescale at a high pumping intensity, and are strongly dependent on the scale of quantum confinement. The calculations fit well with photoluminescence rising times tau = 0.45ps [K. Gundogdu, K.C. Hall, T.F. Boggess, D.G. Deppe, O.B. Shchekin, Appl. Phys. Lett. 85 (2004) 4570.] and tau = 1.7ps [K.W. Sun, A. Kechiantz, B.C. Lee, C.P. Lee, Appl. Phys. Lett. 88 (2006) 163117.] which are observed in the experiments on p-doped InAs quantum dots. (C) 2007 Elsevier B.V. All rights reserved.