氮化物抛物量子阱中电子-声子相互作用对极化子能量的影响

采用改进的LLP变分方法．研究氮化物抛物量子阱（GaN／Al0.3Ga0.7N）材料中的电子-声子相互作用．给出极化子基态能量、第一激发态到基态的跃迁能、不同支长波光学声子模对极化子基态能量的贡献随阱宽L的变化关系，在数值计算中考虑了氮化物（纤维锌矿）GaN和AlxGa1-xN构成的抛物量子阱材料中长波光学声子模的各向异性．结果表明，基态能量和跃迁能量随阱宽L的增大而减小。阱宽较小时．减小的速度比较快＋阱宽较大时．减小的速度比较慢．最后缓慢地接近GaN体材料中的三维值．在GaN／Al0.3Ga0.7N抛物量子阱中定域准LO声子对极化子能量的贡献比较大．阱宽较大（L=27nm）时约33meV，这一值比GaAs／Al0.2Ga0.7As抛物量子阱中的相应值（约3meV）大的多，并且定域准LO声子的贡献远远大于定域准TO声子的贡献．

The Effects of the Electron-Phonon Interaction on the Energy of a Polaron in Nitride Parabolic Quantum Well

Interaction of the electron-phonon in GaN/Al_(0.3)Ga_(0.7)N parabolic quantum well was investigated by modified LLP's variational method.The ground state energy,the transition energy(from first excited state to ground state) and the contribution of different branches optical phonon modes to the ground state energies of the polaron in a GaN/Al_(0.3)Ga_(0.7)N parabolic quantum well as functions of the well width L were given.In numerical calculation,anisotropy of the optical phonon modes in nitride(wurtzite) was considered.The results showed that the ground state and the transition energy of the polaron(decrease) with increasing well width L.The speed of decreasing is very quickly at small L,then slowly,and(finally) close to the 3D-value in GaN.Contribution of LO-like mode to the ground state energy in a(GaN/Al_(0.3)Ga_(0.7)N) parabolic quantum well is very large,about 33 meV at larger well width(L=27 nm),and the value is larger than the corresponding value(about 3 meV) in GaAs/ Al_(0.3)Ga_(0.7)As parabolic quantum well.At the same time,the contribution of the LO-like mode to the ground state energy is much larger than that of TO-like mode in a GaN/Al_(0.3)Ga_(0.7)N parabolic quantum well.Therefore,the coupling of the(electron)-LO-like mode is important in the GaN/Al_(0.3)Ga_(0.7)N parabolic quantum well when electron states are discussed.