The Effect Of Well Width And Composition To Polaron Energy In Wurtzite ZnO/Mg_xZn_1-xO Quantum Well

The effects of electron-phonon interaction on polaron energy level in the wurtzite Zn O/ MgxZn1-xO and InxGa1-xN/GaN quantum well are analysed by the method of LLP variational.The ground state energy, transition energy,excited state energy, and effects of the electron-phonon interaction on polaron energy are given as functions of well width d and composition x. The anisotropy of the confined phonon and half-space phonon frequency, and dielectric constant are considered in the investigation of wurtzite ZnO/Mgx Zn1-xO and InxGa1-xN/GaN quantum well material. The results show that the effect of confined phonons modes on system energy appear rapid growth at first, then slow growth, and finally approaches to the bulk material value with increasing the well width d in the wurtzite Zn O/ MgxZn1-xO and InxGa1-xN/GaN quantum well material. The effect of half-space phonon mode on the system level is opposite to that of confined phonon mode, and finally system energy shift approach to zero. The total shifts of two kindes of phonon mode(35 meV to 66 me V) on system energy in the ZnO/Mg0.3Zn0.7O quantum well materials are larger than that(16 meV to 31 meV) in In0.3Ga0.7N/GaN quantum well materials. With increasing the well width, the influence of electron-phonon interaction on the ground state energy, and the ground state energy, the excited state energy and the transition energy all decrease.The influence of the half-space phonon mode on the system leveldecrease with increasing composition x(range 0.1 to 0.4) in these two kinds of quantum well material for given well width 7 nm, but the influence of confined phonon mode to the system energy increase in the ZnO/MgxZn1-xO quantum well material, and decrease in the InxGa1-xN/GaN quantum well material. The influence of electron-phonon interaction on the ground state energy, and the ground state energy, the excited state energy, and transition energy all change large with the increases of composition x for given well width(7 nm and 15 nm). Morever, the increase tendency in narrow well are greater than that of the corresponding value in wide well. It is found by researching and analyzing that the factors of influencing the energy of polaron in wurtzite quantum well not only relate to quantum well structure but also relate to th electron-phonon interaction in the quantum well.