Effect of hydrostatic pressure on the donor impurity states in GaN/AlGaN asymmetric coupled quantum wells

Based on the effective-mass approximation, the ground-state donor binding energy in zinc-blende(ZB) GaN/AlGaN asymmetric coupled quantum wells(QWs) is investigated variationally, considering the hydrostatic pressure effect. Numerical results show that the donor binding energy is highly dependent on the impurity positions, the asymmetric coupled QWs structure parameters and the hydrostatic pressure. It is found that the donor binding energy increases with increase in the hydrostatic pressure for any impurity position. The hydrostatic pressure has an obvious influence on the donor binding energy of impurity localized inside the wide well of the asymmetric coupled QWs. For any hydrostatic pressure, our results show that the donor binding energy is distributed asymmetrically with respect to the center of the asymmetric coupled QWs. In particular, for the impurity located inside the wide well, the donor binding energy is insensitive to the middle barrier width in ZB GaN/AlGaN asymmetric coupled QWs if the middle barrier width is large.