Site and sample dependent electron-phonon coupling of Eu ions in epitaxial-grown GaN layers
Site and sample dependent electron-phonon coupling of Eu ions in epitaxial-grown GaN layers
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DOI：
10.1016/j.optmat.2010.09.029
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发表时间：
2011-05-01
影响因子：
3.9
通讯作者：
Dierolf, V.
中科院分区：
文献类型：
--
作者：
Woodward, N.;Nishikawa, A.;Dierolf, V.
采用有机金属气相外延（OMVPE）生长过程中原位掺杂的样品的联合激发-发射光谱法研究了Eu离子掺入GaN。随后使用所获得的特征发射光谱的指纹来确定Eu离子与晶格的耦合。我们发现了一个多数网站，这表现出耦合到批量样的声子模式，以及本地化的声子模式。对于这个位置，我们还发现（7）F（0）到（5）D（0）跃迁的零声子线，这是被禁止的，比声子耦合激发跃迁弱得多。零声子与声子耦合跃迁强度的比率取决于层的结晶质量。这些观察结果是一致的多数网站的未扰动的Eu离子Ga位置上的分配。我们发现，当用零声子（7）F（0）到（5）D（0）激发跃迁作为量度时，大多数位置的相对丰度被严重低估。由爱思唯尔公司出版
The incorporation of Eu ions into GaN has been studied using combined excitation-emission spectroscopy for samples that were in situ doped during organometallic vapor-phase epitaxy (OMVPE) growth. The obtained fingerprints of characteristic emission spectra are subsequently used to determine the coupling of the Eu ions to the crystal lattice. We find a majority site, which exhibits coupling to bulk-like phonon modes as well as a localized phonon mode. For this site, we also find that the zero-phonon line of the (7)F(0) to (5)D(0) transition, which is forbidden, is much weaker than the phonon-coupled excitation transitions. The ratio of zero-phonon to phonon-coupled transition strength depends on the crystalline quality of the layer. These observations are consistent with the assignment of the majority site to an unperturbed Eu ion on Ga position. We find that the relative abundance of the majority site is strongly underestimated whenever the zero-phonon (7)F(0) to (5)D(0) excitation transition is used as a measure. Published by Elsevier B.V.