POLARONIC EFFECTS ON THE IMPURITY BINDING-ENERGY IN A POLAR CRYSTAL SLAB WITHIN AN ELECTRIC-FIELD

The effects of the interaction between electron and bulk longitudinal optical (LO) phonon and surface optical (SO) phonon on the impurity bi nding energy of the ground state in a polar crystal slab within an ext ernal electric field are derived by using the method of a variational wavefunction. The binding energy of the bound polaron is obtained as a function of the impurity position, the slab thickness and the electri c field strength. It is found that the polaronic correction to the imp urity binding energy by the SO phonon may be enhanced and that by the LO phonon may be reduced with increasing electric held strength. And t he effect of the electron-phonon interaction is quite important in inc reasing the values of binding energy.