Using a variational procedure within the effective mass approximation we calculate the binding and transitions energies of a shallow-donor impurity in spherical quantum dots with parabolic confinement (QDP), as a function of both the applied electric field and the radius of the quantum dot. We have found that the geometric confinement and the intensity of the electric field are determinant for the existence of bounded excited states in these structures. Likewise, we have found that the transition energies decrease with the radius and the intensity of the applied electric field.