  We present an exact calculation of the single-electron energies and
wave-functions for any bound state in a realistic Si-SiO2 spherical quantum
dot, including the material dependence of the electron effective mass. The
influence of dot radius, confinement barrier potential and barrier-to-dot
electron mass ratio on the electronic structure is investigated in detail. The
results show that the energy structure shifts down from some tens to some
hundreds meV compared to that obtained in the simplified model where the change
in effective mass is neglected. Our exact single-electron calculation is
finally used to verify the accuracy of the results obtained from a numerical
approximate method developed to treat many-electron systems.
