Abstract
In the present work we calculate, by a variational approach, the binding energy of an on-axis hydrogenic donor as a function of the radius of the quantum-well wire. In addition, we also discuss the screening of a (point) donor ion by the valence electrons of GaAs and calculate, again by a variational approach, the binding energy of an on-axis nonhydrogenic donor as a function of the radius of the quantum-well wire. In these calculations we use a wave function suggested a few years ago by Lee and Spector.