Green luminescence band in ZnO: fine structures, electron-phonon coupling, and temperature effect.
Green luminescence band in ZnO: fine structures, electron-phonon coupling, and temperature effect.
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DOI：
10.1021/jp0610968
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发表时间：
2006-05
期刊：
影响因子：
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通讯作者：
S. Shi;Guangqi Li;Shijie Xu;Yang Zhao;Guanhua Chen
中科院分区：
文献类型：
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作者：
S. Shi;Guangqi Li;Shijie Xu;Yang Zhao;Guanhua Chen
本文从理论和实验两方面研究了ZnO的绿色发射带。在低温宽绿色发射光谱中，可以很好地分辨出两组具有相同周期性（接近ZnO的纵光学（LO）声子能量）的均匀分离的精细结构。随着温度的升高，精细结构逐渐淡出，整个绿色发射带在室温下变得平滑。尝试定量再现变温绿色发射光谱使用欠阻尼多模布朗振子模型考虑到量子耗散效应的声子浴。结果表明，这两个电子跃迁与ZnO的晶格振动强耦合，导致了观察到的具有精细结构的宽发射带。在整个温度范围内理论与实验之间的良好一致性使我们能够确定表征电子-LO声子耦合强度的无因次Huang-Rhys因子以及LO和浴模的耦合系数。
The green emission band of ZnO has been investigated by both experimental and theoretical means. Two sets of equally separated fine structures with the same periodicity (close to the longitudinal optical (LO) phonon energy of ZnO) are well resolved in the low-temperature broad green emission spectra. As the temperature increases, the fine structures gradually fade out and the whole green emission band becomes smooth at room temperature. An attempt to quantitatively reproduce the variable-temperature green emission spectra using the underdamped multimode Brownian oscillator model taking into account the quantum dissipation effect of the phonon bath is done. Results show that the two electronic transitions strongly coupled to lattice vibrations of ZnO lead to the observed broad emission band with fine structures. Excellent agreement between theory and experiment for the entire temperature range enables us to determine the dimensionless Huang-Rhys factor characterizing the strength of electron-LO phonon coupling and the coupling coefficient of the LO and bath modes.