In recent years

the experimental advance has stimulated interest in semiconductor quantum wells and heterojunctions to explore the novel phenomena and their applications.Some authors investigated the shallow donors in quantum well with presence of a magnetic field.But few studies focused on the states of impurities near the heterojunction interface with the external magnetic field

especially in consideration of the electronic screening effect.A variational method is adopted to investigate the binding energies of shallow donor impurities near the interface of a single semiconductor heterojunction system in the presence of a static uniform magnetic field by considering a triangular potential to approximate the interface potential.The electronic image potential and the screened Coulombic impurity potential are also taken into account to investigate the impurity state binding energy.Numerical computation has been performed for the GaAs/Al

x

Ga

1-x

As structure.For a given impurity position the binding energy as a function of magnetic field

perpendicular to the interface

shows a monotonic increase tendency with increasing the magnetic field strength B

which makes the electronic wave functions highly localized to magnify the effective Coulombic attraction.This monotonic property is different from the maximum property obtained by Hollox.The binding energy is also computed as a function of the impurity position

z

0

to show that the binding energy increases at first

and then decreases with increasing the distance between the impurity and the interface.The results corresponding to with and without the screening effect are compared.It is found that even in the presence of a magnetic field the screening effect dramatically decreases the impurity state binding energy

which is obviously influenced by the barrier potential and the conduction band bending.The binding energy is sensitive to the areal electron density.It is also found that the influence of the electron image potential is negligibly small so that it needs to be considered in the further discussion.This is consistent with the early conclusion for without a magnetic field case.