IONIZED DONOR IMPURITY IN A SEMICONDUCTOR QUANTUM-WELL

We present the results of a variational calculation of the ground stat e energy of a (D+,X) complex in a quantum well with finite potential b arriers as a function of the depth and the width of the well as well a s the ratio sigma of the electron and hole effective masses. We use th e envelope function approximation. We apply our results to the system GaAs/Ga1-xAlxAs with x = 0.15 and x = 0.30. It appears that the coulom bic correlation energy goes through a minimum for a well thickness in the order of 50 Angstroms. This minimum is comprized between the value s obtained in the 2D and 3D limit cases. Furthermore, it appears that only the heavy hole states give rise to a stable binding energy for al l values of the well thickness. The light hole states give rise to sta ble binding only in the case of large thicknesses.