Incomplete confinement of electrons and holes in microcrystals

A simple variational calculation is presented for the ground-state energy of an electron-hole system confined in a microcrystal with finite potential barriers. It is shown that the effect of the penetration of the wave function outside the microcrystal is quite large in the strong-confinement region and is consistent with the relatively small blueshift of the excitation energy observed in CdS microcrystals.