DIRECT PSEUDOPOTENTIAL CALCULATION OF EXCITON COULOMB AND EXCHANGE ENERGIES IN SEMICONDUCTOR QUANTUM DOTS

The effects of electron-hole interaction on the exciton energy of semi conductor quantum dots are calculated using pseudopotential wave funct ions. A comparison with the widely used, but never tested, effective-m ass approximation (EMA) shows that the electron-hole Coulomb energy is significantly (similar to 40%) overestimated by the EMA, and that the scaling with the dot size R is sublinear in 1/R. The exchange splitti ng is much smaller than the Coulomb energy, and in the case of CdSe qu antum dots shows significant deviations from the 1/R(3) scaling predic ted by the EMA.