Radiative recombination in InAs-based quantum dot lasers: dependence on carrier density and dot parameters



The radiative recombination rate in InAs-based quantum dot lasers has been studied theoretically in the framework of an 8 × 8 k · p model. It is shown that the optical matrix element for transitions between the excited electron-hole states in a quantum dot is usually smaller than that for the ground-state transition. As a consequence, the total radiative recombination rate R in a quantum dot laser depends on the carrier density as R = B(N)N2 with the radiative recombination coefficient B(N) being a strong function of the carrier density N. We find that the recombination coefficient decreases with the carrier density N, and its variation with N depends strongly on the quantum dot shape and size. We conclude that the commonly accepted model that the radiative current density varies quadratically with carrier density N is in general not valid for quantum dot laser structures. (© 2005 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim)