We improve upon Singh et al.'s simple method [Phys. B53, 15909 (1996)] to calculate 2D biexciton binding energy in quantum wells. Optimising the geometric structure, a simple and analytical expression for the ratio of the binding energy of a 2D biexciton to that of an exciton, B_b~(xx)/B_b~x, is derived. In this calculation, we find that B_b~(xx)/B_b~x depends on the mass ratio sigma =0.68 which agrees very well with the experimental value. We also find that the structural configuration of a positronium- molecule-like biexciton ( sigma =1) is a square and that of a hydrogen-molecule-like biexciton ( sigma =1) is a tetragon with /=1.292 and /=1.581.
展开▼
