POLARON EFFECT ON D- CENTERS IN WEAKLY POLAR SEMICONDUCTORS

The polaron correction to the energy of the two-electron bound (D-) st ates of a shallow donor in weakly polar semiconductors is calculated. Both upper and lower bounds to the energy shift of the ground state an d also to the D- transition energy are derived within second-order per turbation theory. The results show a stronger polaron effect in these systems than for two independent single-electron systems. The polaron correction to the D- level depends strongly on the properties of the e lectron-phonon interaction and/or the relative position of the two ele ctrons. [S0163-1829(98)01207-7].