Abstract: The energy levels of donors in quantum wells with finite barriers are investigated using a variational method.We consider the variations of the electron effective mass,dielectric constant,and conduction band offset between the well and barriers with hydrostatic pressure,and we take into account the screening effect on the Coulombic potential of an impurity from the 2D electron gas.Numerical calculations are performed for the binding energies of impurity states in GaAs/Al_xGa_1-xAs quantum well systems.The relations between the binding energies of donors and Al concentration,well width,and hydrostatic pressure are given.The difference between the cases with and without screening is discussed.The results indicate that the screening increases with pressure,resulting in a decrease in the binding energies of the impurity states.

Key words: quantum well, screening, pressure, impurity state binding energy, 结合能