In this work, we report on three new extremely sharp emission lines in zinc oxide (ZnO) related to iron–lithium complexes. The identification is based on a comparison of hydrothermally grown ZnO with high lithium concentration and a lithium-free sample grown by methane based chemical vapor deposition, which both were implanted with iron. After annealing in a mixed oxygen/argon atmosphere at $800{}^{°}\mathrm{C}$, the lithium-free sample showed no additional lines besides the well-known emission at $693\mathrm{nm}$ $({1.7873}_4\mathrm{eV})$, whereas the hydrothermally grown sample emitted three intense and sharp lines in photoluminescence (PL) spectroscopy. These emission lines at $705\mathrm{nm}$ $({1.7587}_3\mathrm{eV})$, $712\mathrm{nm}$ $({1.7415}_3\mathrm{eV})$, and $732\mathrm{nm}$ $({1.6928}_3\mathrm{eV})$ were characterized by temperature dependent high resolution continuous wave (cw) and time-resolved PL spectroscopy, as well as by photoluminescence excitation spectroscopy, and are assigned to different Fe–Li complexes. We find a single thermally activated excited state for each of the complex emission lines, different from the ${}^4{\mathrm{T}}_1{\to }^6{\mathrm{A}}_1$ transition of ${\mathrm{Fe}}^{3+}$ with its at least three excited states. While time-resolved photoluminescence measurements of the ${\mathrm{Fe}}^{3+}$ transition show a lifetime of $24.9\pm 0.5\mathrm{ms}$, we find a reduced lifetime of $8.5\pm 1\mathrm{ms}$ for the new zero phonon lines, pointing to stronger mixture of the Fe 3d states with surrounding p-orbitals.

中文翻译：

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ZnO中铁锂复合物的发射

在这项工作中，我们报告了与铁锂复合物有关的氧化锌（ZnO）中的三种新的极尖锐的发射谱线。鉴定是基于对高锂浓度的水热生长的ZnO和通过甲烷基化学气相沉积法生长的无锂样品进行比较的方法，二者均注入了铁。在氧气/氩气混合气氛中于$800{}^{°}\mathrm{C}$，不含锂的样品除了在 $693\mathrm{纳米}$ $（{1.7873}_4\mathrm{电子伏特}）$，而水热生长的样品在光致发光（PL）光谱中发出了三条强烈而清晰的线条。这些发射线位于$705\mathrm{纳米}$ $（{1.7587}_3\mathrm{电子伏特}）$， $712\mathrm{纳米}$ $（{1.7415}_3\mathrm{电子伏特}）$， 和 $732\mathrm{纳米}$ $（{1.6928}_3\mathrm{电子伏特}）$通过与温度相关的高分辨率连续波（cw）和时间分辨PL光谱以及光致发光激发光谱对其进行表征，并分配给不同的Fe-Li络合物。我们发现每个复杂的发射谱线都有一个热激活的激发态，这与激发态不同。${}^4{\mathrm{Ť}}_{\mathrm{1个}}{\to }^6{\mathrm{一种}}_{\mathrm{1个}}$ 过渡 ${\mathrm{铁}}^{3+}$至少具有三个激发态 而时间分辨的光致发光测量${\mathrm{铁}}^{3+}$ 过渡显示一生 $24.9\pm 0.5\mathrm{小姐}$，我们发现寿命缩短了 $8.5\pm \mathrm{1个}\mathrm{小姐}$ 对于新的零声子线，表明Fe 3d态与周围p轨道的混合更强。