Effect of an image potential on the ground-state energy of shallow-donor impurities near the surface of semi-infinite crystals

Abstract
The effect of image potential on the ground-state energy of a shallow-donor impurity near a sharp surface of a semi-infinite crystal is studied. A simple but realistic trial function is used in the confocal elliptic coordinate system with the foci at the hydrogenic donor impurity and its image point. The ground-state energy of this system is calculated as a function of the impurity position.