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首页> 外文期刊>Physica, B. Condensed Matter >Interstitial carbon-related defects in Si1-xGex alloys
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Interstitial carbon-related defects in Si1-xGex alloys

机译：Si1-xGex合金中与碳有关的间隙缺陷

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The interstitial carbon (C-I) impurity vibrational modes in monocrystalline Si-rich SiGe compounds were investigated by Fourier Transform Infra Red spectroscopy and density functional modeling. The two absorption bands of C, are found to be close to those in Si, but lines show shifts in opposite directions with increasing Ge content. The transversal mode band at 932 cm(-1) shifts slightly to the high-frequency side, while the longitudinal mode at 922 cm(-1) suffers a pronounced red-shift. Each Cl-related band is found to consist of two components. Such two-component structure of bands is suppose most likely to correspond to different combinations of Si and Ge atoms in the neighborhood of the C-I atom. C-I in Si1-xGex was found to begin to anneal at lower temperature than in Si and occurs in two stages. During the first stage (210-250 K) the main components of bands anneals and revealed components grow in intensity. At T>250K all components start to disappear. The C-I defect was modeled by a supercell density-functional pseudopotential method (AIMPRO). From energetics, it has been found that each Ge-C bond costs at least 0.4 eV in excess of a Si-C bond. The vibrational mode frequencies taken from several randomly generated SiGe cells produce the observed opposite shifts for the transverse and longitudinal modes. However, structures where Ge atoms are second neighbors to the C atom are marginally bound, and may explain the two-component band structure in the absorption measurements. (C) 2007 Elsevier B.V. All rights reserved.
机译：通过傅立叶变换红外光谱和密度泛函模型研究了单晶富硅SiGe化合物中的间隙碳（C-1）杂质振动模式。发现C 1的两个吸收带接近Si中的吸收带，但是随着Ge含量的增加，线显示出在相反方向上的位移。横向模式带在932 cm（-1）处向高频侧稍有偏移，而纵向模式在922 cm（-1）处出现明显的红移。发现每个与Cl有关的带均由两个成分组成。这种带的两组分结构被认为最可能对应于C-1原子附近的Si和Ge原子的不同组合。发现Si1-xGex中的C-1在低于Si的温度下开始退火，并分两个阶段发生。在第一阶段（210-250 K）中，带的主要成分退火，并且显露的成分强度增加。在T> 250K时，所有组件开始消失。 C-1缺陷是通过超细胞密度函数假电位方法（AIMPRO）建模的。从能量学上，已经发现每个Ge-C键的成本至少比Si-C键高0.4eV。从几个随机生成的SiGe单元获取的振动模式频率会产生横向和纵向模式的相反位移。但是，Ge原子是C原子的第二邻居的结构是有限边界的，并且可以解释吸收测量中的双组分带结构。 （C）2007 Elsevier B.V.保留所有权利。

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