纤锌矿GaN／AlxGa1-xN量子阱中极化子能量

Energy of Polaron in Wurtzite GaN/Al_xGa_(1-x)N Quantum Well

采用LLP变分方法研究了纤锌矿GaN/AlxGa1-xN量子阱材料中极化子的能级,给出极化子基态能量、第一激发态能量和第一激发态到基态的跃迁能量与量子阱宽度和量子阱深度变化的函数关系。研究结果表明,极化子基态能量、第一激发态能量和跃迁能量随着阱宽L的增大而开始急剧减小,然后缓慢下降,最后接近于体材料GaN中的相应值。基态能量和第一激发态到基态的跃迁能量随着量子阱深度的增加而逐渐增加,窄阱时这一趋势更明显。纤锌矿氮化物量子阱中电子-声子相互作用对能量的贡献比较大,这一值(约40meV)远远大于闪锌矿(GaAs/AlxGa1-xAs)量子阱中相应的值(约3meV)。因此讨论GaN/AlxGa1-xN量子阱中电子态问题时应考虑电子-声子相互作用。

In this paper, the energy levels of polarons in the wurtzite GaN/AlxGa1-xN quantum well structure are studied by using Lee-Low-Pines （LLP） transition. The ground state, first excited state and transition energies from first excited state to ground state are calculated as a function of well width （L） and depth （V0）. The results indicate that the ground state, first excited state and transition energies rapidly decrease with increasing the well width at smaller L, but slowly at larger L, and finally approach to the bulk value of GaN. The ground state, first excited state and transition energies all slowly increase with increasing Vo, and it is more visible in narrow well. It is also found that the contribution of electron-phonon interaction in wurtzite nitride quantum well structure is very large, the value （ about 40 meV） is much larger then that （ about 3 meV） in zinc-blende （GaAs/AlxGa1-xAs） quantum well structure. Therefore, the contribution of electron-phonon interaction in wurtzite GaN/AlxGa1-xN quantum well structure should be considered when the problem of election state is discussed.