Electronic states of impurities located at or near semiconductor–insulator interfaces

We solve the effective mass equations describing donor impurities localized at semiconductor–insulator interfaces using a method which involves an expansion of the impurity wavefunction in terms of spherical harmonics. We also investigate the behavior of the impurity energies as a function of the donor distance from the interface both in the insulator and in the semiconductor. This allows, for the first time, the connection between surface and bulk donor properties. Results for the Si–SiO2 case are presented.