Binding Energy of Biexcitons in Two-Dimensional Semiconductors

The binding energies of a two-dimensional (2D) biexciton have been calculated variationally for all values of the effective electron-to-hole mass ratio u by using a three-parameter wave function. The ratio of the binding energy of a 2D biexciton to that of a 2D exciton is found to be from 0.582 to 0.220. The results agree fairly well with previous experimental results. The results of this approach are compared with those of earlier theories.