Effects of hydrogenic donor impurity position on the binding energy of a bound exciton in III-nitrides quantum dots

In this paper,concerning the domino effect of the built-in electric field and the three-dimension confinement,the effects of hydrogenic donor impurity position on the binding energy of a bound exciton in Ⅲ-nitrides quantum dots(QDs) are investigated by means of a variational approach within the framework of effective-mass approximation.The numerical results show that there are critical values on the height of the QDs and In content when there is a hydrogenic donor impurity in the center of In_xGa_(1-x)N/GaN quantum dots.The exciton binding energy and stability of exciton state are increased,when the parameter is larger than the critical value and the exciton dissociation temperature rises.So the exciton absorption peak in the absorotion spectrum of the QDs can be observed in higher temperatures.The exciton binding energy is increased with introducing the impurity into GaN/Al_xGa_(1-x)N quantum dots.The carriers are more strongly confined in the QDs,and the exciton in QDs can be observed in higher temperatures.The influence of the hydrogenic donor impurity position on the exciton binding energy is also investigated in the paper.The results show that the exciton binding energy is the highest and the stability of exciton state is the strongest when the impurity position is on the upper interphase of QDs.As the impurity moves to lower interphase of QDs,the binding energy reduces,and the exciton dissociation temperature drops.