EXCITONS IN TYPE-II QUANTUM DOTS - BINDING OF SPATIALLY SEPARATED ELECTRON AND HOLE

The quantum size effect for the binding energy of an exciton in a sphe rical quantum dot is studied theoretically. We use a variational appro ach and assume that the electron and hole are separated by infinite of fsets. The dependence of the exciton binding energy upon the dot radiu s R is calculated for various sets of hole and electron effective mass es. The spatial structure of the bound electron-hole pair is qualitati vely different in the two regimes in which the dot radius R is either much smaller or much larger than an effective Bohr radius of the excit on in bulk.