Collisional processes involved in the population kinetics of semiconductor quantum-dot lasers.

Abstract

We present an application to quantum dots of formulas from atomic physics for the rates of collisional ionization (binary encounter model) and dipole allowed collisional excitation (Van Regemorter and classical path models) occurring via the Coulomb interaction. The Van Regemorter, classical path, and binary encounter cross sections, which are known to be very successful in modeling atomic collisions, are shown to have accuracies comparable to (and are much easier to use than) the methods currently being used to study collisional rates in bulk excitons. Collisional excitation and ionization cross sections for a 150-\AA{}-radius InSb quantum dot surrounded by CdTe barriers are shown to be much smaller than the geometric area \ensuremath{\pi}${\mathit{R}}^{2}$, where R is the quantum-dot radius. The reason that these cross sections are so small is that the Coulomb energy associated with the collision is typically much smaller than the collisional energy exchange. Explicit formulas are given for quantum-dot intraband oscillator strengths.