Size dependence of the electron-hole recombination rates in semiconductor quantum dots

The size dependence of the radiative recombination rates of electrons and holes confined in a semiconductor InGaAs/GaAs quantum dot has been studied using large configuration interaction (CI) expansions. The confinement potentials were modeled by employing truncated two-dimensional parabolas. The calculations show that the radiative recombination rates from the ground states of the (multi)excitons are rather smooth functions of the dot size; no “magic” dot sizes with exceptional fast radiative recombination rates were found, but level crossings cause significant variations. The recombination rates calculated at the CI level are much larger than those obtained at the self-consistent-field (SCF) and free-particle (FP) levels. The exciton ground-state recombination rate increases monotonously with increasing dot radius, whereas at the SCF and FP levels the recombination rate is independent of the dots radius. Thus Coulomb correlation effects are necessary for explaining the predicted size dependences.