论文标题
si $ _x $ ge $ _ {1-x-y} $ sn $ _y $ y $合金匹配ge/gaas的直接过渡能量的成分依赖性
Compositional dependence of direct transition energies in Si$_x$Ge$_{1-x-y}$Sn$_y$ alloys lattice-matched to Ge/GaAs
论文作者
论文摘要
Si $ _x $ ge $ _ {1-x-y} $ sn $ _y $ ternary Alloys是用于太阳能电池和其他光电设备的候选材料系统。我们报告了Ge-ge-ge-rich si $ _x $ ge $ _ {1-x-y} $ sn $ _y $ $ y $合金的直接过渡能和结构属性，具有六种不同的构图，最高10％SI和3％SN，lattice匹配给GE GE或GAAS底物。使用光谱椭圆法（SE）研究了发生0.9和5.0 eV之间的直接过渡，并使用所得数据来获得Si $ _x $ _x $ ge $ _ {1-x-x-y} $ sn $ sn $ _y $ n层的介电函数，通过拟合多层模型。然后通过区分这些介电功能来提取关键点的位置，可以找到$ e_0 $，$ e_1 $，$ e_1 $，$δ_1$，$ e_0' $和$ e_2 $ transition Energies的值。在结构上，使用能量分散性X射线测量（EDX）测量样品的组成。这些组合物预测的晶格常数与通过X射线衍射（XRD）获得的相互空间图非常吻合。结果证实，使用相对较低的Si和SN分数（分别<$ <$ 10％和$ <$ 3％）可以实现1 eV的直接吸收边缘，而较高能量的临界点相对于GE显示了较小的变化，并且在文献中观察到或预测。
Si$_x$Ge$_{1-x-y}$Sn$_y$ ternary alloys are a candidate material system for use in solar cells and other optoelectronic devices. We report on the direct transition energies and structural properties of Ge-rich Si$_x$Ge$_{1-x-y}$Sn$_y$ alloys with six different compositions up to 10 % Si and 3 % Sn, lattice-matched to Ge or GaAs substrates. The direct transitions occurring between 0.9 and 5.0 eV were investigated using spectroscopic ellipsometry (SE), and the resulting data was used to obtain the dielectric functions of the Si$_x$Ge$_{1-x-y}$Sn$_y$n layer by fitting a multi-layer model. Values for the $E_0$, $E_1$, $Δ_1$, $E_0'$ and $E_2$ transition energies were then found by differentiating these dielectric functions to extract the locations of critical points. Structurally, the composition of the samples was measured using energy-dispersive X-ray measurements (EDX). The lattice constants predicted from these compositions are in good agreement with reciprocal space maps obtained through X-ray diffraction (XRD). The results confirm that a 1 eV direct absorption edge can be achieved using relatively low Si and Sn fractions ($<$ 10 % and $<$ 3 % respectively), while the higher-energy critical points show smaller shifts relative to Ge and match results previously observed or predicted in the literature.
