Stability of an exciton bound to an ionized donor impurity in a GaAs/Ga1-xAlx semiconductor quantum well in a magnetic field

We discuss the stability of an exciton bound to an ionized donor impurity in a GaAs/Ga1-xAlxAs semiconductor quantum well subjected to an external magnetic field for different values of the impurity location. The binding energy is calculated in the effective mass approximation by means of variational method. At zero magnetic field, the complex becomes unstable when the impurity is far away from the center of the well. When the magnetic field increases, the stability holds in all cases for an impurity located at the center of the well. (C) 2002 Elsevier Science B.V. All rights reserved.