Uniaxial stress dependence of the binding energy of shallow donor impurities in GaAs-(Ga,Al)As quantum dots

We have studied the effects of an uniaxial stress on the binding energy of a shallow donor impurity in a parallelepiped-shaped GaAs-(Ga,Al)As quantum dot. In the calculations we have used a variational technique within the ef fective-mass approximation. The stress was applied in the z direction and t he donor impurity was located at various positions along the z axis. Our re sults show that the donor binding energy increases with increasing stress a nd for decreasing sizes of the quantum dot. Also, we have found that the bi nding energy for various values of the donor position along the z axis for constant quantum well box size increases with the proximity of the impurity to the center of the structure. Moreover, we obtain the shallow-donor bind ing energies as functions of uniaxial stress in the limit in which the quan tum dot turns into either a quantum well or a quantum-well wire. (C) 2001 A merican Institute of Physics.