Impurity States And Bound Polaron In The Strained Nitride Semiconductor Rectangle Quantum Dot

Within the effective-mass approximation, the hydrostatic impurity binding energy in a finite potential spherical quantum dot under an applied electric field and hydrostatic pressure are studied. The effects of interaction between the charge carrier (electron and ion) with the local and half-space LO phonons to binding energy has been studied in our study using a Lee-Low-Pines (LLP) variational treatment.Firstly, The effects of hydrostatic pressure and electric field on the impurity binding energy in GaN/AlxGa1-xN spherical quantum dot are calculated using a variational method based on the effective mass approximation. The binding energies are computed as a function of dot size and hydrostatic pressure. The numerical results show that the binding energies of the impurity state increase, attain a maximum value, and then decrease as the quantum dot radius increases for any electric field. Moreover, the binding energies increase with the pressure for any size of dot. The Stark shifts of the impurity energy for large dot size is much larger than that for the small dot size, and it is enhanced by the increase of electric field. We also take the dielectric mismatch in this structure into account in our work.Secondly, the polaronic effect on the binding energy of hydrogenic impurity in spherical quantum dot in presence of an electric field and hydrostatic pressure are calculated by Lee-Low-Pines (LLP) variational treatment. The effects of interaction between the electron and ion with the LO phonons to binding energy are calculated respectively. The results show that the interaction of the charge carriers with the optical phonons greatly decreases the binding energy. The interaction of the electron with the local LO phonons is increases the binding energy. However, the interaction of the electron with the half-space LO phonons is decreases the binding energy. Moreever, the interaction of the impurity with LO phonons play a major role in the polaronic effect, polaronic effects enhanced by the increase of Al concentration. Stark shifts of binding energy are weakened by the polaronic effect.