Effects of an electric field on the binding energy of a donor impurity in a spherical GaAs-(Ga,Al)As quantum dot with parabolic confinement

The binding energy of a donor impurity in a spherical GaAs-(Ga,Al)As quantu m dot with parabolic confinement is calculated as a function of the radius of the quantum dot and as a function of the intensity of an applied electri c field. Calculations are performed within the effective-mass approximation and using a variational method. We have found that when the radius of the quantum dot is reduced, both the energy of the ground state in the well of GaAs and the binding energy of the impurity increase. Likewise, we have fou nd that these energies decrease with the electric field for quantum dots of different radii when the intensity of the electric field is increased. Fin ally we compare our results with previous reports in quantum dots.