Binding energy of the ground and first few excited states of a shallow-donor impurity in rectangular-cross-sectional area GaAs quantum-well wires under applied electric field

Using a variational approach within the effective mass approximation we cal culate the binding energy of the ground and some excited donor impurity sta tes in quantum-well wires with rectangular and cylindrical transversal sect ions under the action of applied electric fields. We study the binding ener gy as a function of the geometry of the system, the applied electric field as well as the impurity position inside the structure. We found that the pr esence of the electric field breaks down the degeneracy of states for impur ities symmetrically positioned within the structure, and that the geometric confinement and the electric field are determinant for the existence of bo und excited states in these structures.