Biexcitons bound to single-island interface defects

Abstract

We calculate the binding energy of biexcitons bound to single-island interface defects in deep quantum wells. The application of a variational function leads to a calculation that is mostly analytical. We discuss in detail the dependence of the biexciton binding energy on the defect size and the quantum-well width. The numerical calculations are carried out for ${\mathrm{Al}}_{x}{\mathrm{Ga}}_{1\ensuremath{-}x}\mathrm{A}\mathrm{s}/\mathrm{G}\mathrm{a}\mathrm{A}\mathrm{s}$ quantum wells with defect depths of 1 and 2 monolayers corresponding to recent experimental findings. Furthermore, we attempt to correlate our problem of a localized biexciton with the existing results for free four-particle molecules in different confinement structures and for different mass ratios.