The effects imposed to the electron energy levels Of Si/SiO2 quantum dots by the presence of smooth graded interfaces and interfacial carriers trap is studied. For small diameter quantum dots, while the existence of graded interfaces strongly blue shifts the carrier energy states (up to a few hundred meV), the effect of the interfacial carriers trap is to red shift the energies, but to a lesser extend (under 50 meV). In addition, slight changes in the distance of the carriers trap in relation to the center of the dot does not alter significantly the energy spectrum. (C) 2002 Elsevier Science B.V. All rights reserved.