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采用改进的Lee-Low-Pines(LLP)中间耦合方法研究纤锌矿Mg x Zn1-x O/Mg0.3Zn0.7O抛物量子阱材料中的极化子能级,给出极化子基态能量、跃迁能量(第一激发态到基态)和不同支长波光学声子对电子态能级的贡献随量子阱宽度d的变化规律。理论计算中考虑了纤锌矿Mg x Zn1-x O/Mg0.3Zn0.7O抛物量子阱材料中声子模的各向异性和介电常数、声子(类LO和类TO)频率等随空间坐标Z变化(SD)效应对极化子能量的影响。结果表明,Mg x Zn1-x O/Mg0.3Zn0.7O抛物量子阱中电子与长波光学声子相互作用对极化子能级的移动很大,使得极化子能量明显降低。阱宽较小时,半空间长波光学声子对极化子能量的贡献较大,而定域长波光学声子的贡献较小;阱宽较大时,情况则正好相反。在d的变化范围内,电子与长波光学声子相互作用对极化子能级的移动(约67~79 meV)比Al x Ga1-x As/Al0.3Ga0.7As抛物量子阱中的相应值(约1.8~3.2 meV)大得多。因此,讨论ZnO基量子阱中电子态问题时要考虑电子与长波光学声子的相互作用。
The polaron energy level of the wurtzite Mg x Zn1-x O / Mg0.3Zn0.7O parabolic quantum well material is studied by the improved intermediate coupling method of Lee-Low-Pines (LLP) The contribution of the transition energy (the first excited state to the ground state) and the contributions of the optical phonons of different branches with respect to the energy levels of the electron states vary with the width d of the quantum well. In the theoretical calculation, the anisotropy and dielectric constant of phonon modes in wurtzite Mg x Zn1-x O / Mg0.3Zn0.7O parabolic quantum well materials are considered, and the phonon (class LO and class TO) Effect of Coordinate Z Change (SD) on Polaron Energy. The results show that the interaction between electrons and long-wavelength optical phonons in the Mg x Zn1-x O / Mg0.3Zn0.7O parabolic quantum well greatly shifts the energy levels of the polaron, resulting in a significant decrease in the energy of the polaron. When the well width is smaller, the half-space long-wavelength optical phonon contributes more to the polaron energy, while the localized long-wavelength optical phonon contributes less. When the well width is larger, the situation is opposite. In the range of d, the shift of the polarizer energy level (about 67-79 meV) by the electron-long wavelength optical phonon interaction is less than the corresponding value in the AlxGa1-xAs / Al0.3Ga0.7As parabolic quantum well (About 1.8 ~ 3.2 meV) much larger. Therefore, when discussing the electronic states in ZnO-based quantum wells, the interaction between electrons and long-wavelength optical phonons should be considered.