Donor impurity states in zinc-blende InGaN/GaN asymmetric coupled quantum dots: Hydrostatic pressure effect

Based on the effective-mass approximation, the ground-state donor binding energy in a cylindrical zinc-blende (ZB) InGaN/GaN asymmetric coupled quantum dots (QDs) is investigated variationally, considering the hydrostatic pressure effect. Numerical results show that the donor binding energy increases on increasing the hydrostatic pressure for any impurity position. The hydrostatic pressure has an obvious influence on the impurity localized inside the wide dot of the asymmetric coupled QDs. In the case of any hydrostatic pressure, our results show that the donor binding energy is distributed asymmetrically with respect to the center of the asymmetric coupled QDs. When the impurity is localized inside the middle barrier layer, the donor binding energy has a maximum value with varying the dot height of the asymmetric coupled QDs. Moreover, for the impurity localized inside the narrow dot, the donor binding energy is decreased monotonically on increasing the middle barrier width. In particular, for the impurity located inside the wide dot, the donor binding energy is insensitive to the middle barrier width if the middle barrier width is large in the ZB InGaN/GaN asymmetric coupled QDs.