纤锌矿GaN/Al_xGa_(1-x)N量子阱中界面声子模对极化子能量的影响

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

采用Lee-Low-Pines变分法研究了纤锌矿GaN/AlxGa1-xN量子阱中极化子能量和电子-声子相互作用对极化子能量的影响.理论计算中考虑了定域体声子模和界面声子模的作用,同时考虑了它们的各向异性.给出极化子基态能量、第1激发态能量、跃迁能量(第1激发态到基态),以及电子-声子相互作用对能量的贡献随量子阱宽度和深度(组分)变化的数值结果.为了定性分析和对比还给出了闪锌矿量子阱中的相对应结果.计算结果表明:阱宽较小时界面声子对极化子能量的贡献大于定域声子,阱宽较大时界面声子的贡献小于定域声子.纤锌矿结构中声子对能量的贡献大于闪锌矿结构中的相应值.GaN/AlxGa1-xN量子阱中声子对能量的贡献比GaAs/AlxGa1-xAs量子阱中的相应值大得多,当阱宽为20nm时,电子-声子相互作用能分别约等于-35,-2.5 meV.

Energy of polaron and effects of electron-phonon interaction in wurtzite GaN/AlxGa1-xN quantum well is investigated by using modified LLP variational method.The confined phonon modes,interface phonon modes,and their anistropy are considered.The ground state energy,the excited state energy,the transition energy of polaron,and the contribution of the electron-phonon interaction to the energy with the well width and composition are calculated.In order to compare,the corresponding results in zinc-blende quantum well are given.The results show that the contribution of interface phonon modes to polaron energy are larger than that of the confined modes for narrow wells,and the contribution of the confined modes to polaron energy are larger than that of the contribution of the interface phonon modes for width wells.The contribution of the electron-phonon interaction to the energy of polaron in wurtzite quantum well is larger than that of in zinc-blende quantum well.The contribution of electronphonon interaction to the energy of polaron in GaN/AlxGa1-xN quantum well is much larger than that in GaAs/AlxGa1-xAs quantum well.For example,when the well width is 20 nm,the electron-phonon interaction energy is about-35 meV and-2.5 meV.