Energy levels of a polaron in wurtzite nitride parabolic quantum well under external electric field
外电场作用下纤锌矿氮化物抛物量子阱中极化子能级

The energy levels of a polaron in a wurtzite nitride finite parabolic quantum well(PQW)are studied by a modified Lee-Low-Pines variational method.The ground state of the polaron,the transition energy from first exited state to the ground state and the contribution from different branches of LO(TO)-like phonon modes on energy levels as functions of the well width L and external electric field F in the wurtzite GaN/Al_xGa_ 1-xN PQW are given.The effects of the anisotropy of confined LO(TO)-like phonon modes,the half-space LO(TO)-like phonon modes,the spatial dependence(SD)of effective mass,dielectric constant,phonon frequency,and external electric field on energy levels are considered in the calculation.The results show that the electron-phonon interaction,SD effects and external electric field strongly affect energy levels of a polaron in wurtzite nitride PQW,all of them tend to lower the polaron energy levels.The SD effect decreases with increasing well width L,and finally approaches to zero.The influence of confined LO-like phonon modes on polaron energy levels is greater at large well width,whereas the influence of half-space LO-like phonon modes is smaller,and the situation is reversed at a small well width.The contributions of the electron-phonon interaction to ground state energy of the polaron in wurtzite GaN/Al_xGa_ 1-xN PQW(roughly from 28 to 42 meV)are greater than that in GaAs/Al_xGa_ 1-xAs PQW(roughly from 0.5 to 3.2 meV).In addition,the contribution of the TO-like phonon modes to polaron energy levels is very small and far smaller than that of the LO-like phonon modes.Therefore,the electron-LO-like phonon interaction should be considered while the electron-TO-like phonon interaction can be neglected in studying the electron states in GaN/Al_xGa_ 1-xN PQW.