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Fundamental temperature-dependent properties of the Si nanocrystal band gap

机译：Si纳米晶体带隙的基本温度依赖性

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摘要

Ever since the first reports about low-temperature photoluminescence (PL) measurements of Si nanocrystals Si (NCs), a severe deviation from the equations commonly used to describe the temperature dependence of the band-gap energy for bulk materials was reported. Our analysis reveals that the formerly observed deviation is solely attributed to too high excitation power densities that cause a preferential emission enhancement of the smaller NCs within a size distribution, due to the temperature dependence of the radiative exciton lifetime. We report on the successful fit of the temperature-dependent band-gap energy of quantum-confined silicon. By means of four size-controlled Si NC samples (1.5 to 4.5 nm), we are able to prove the validity of these equations down to liquid He temperatures, if sufficiently low excitation power densities (<500 μW/cm~2) are used. Thereby, it is shown that the characteristics of the band-gap widening of quantum-confined nanocrystalline Si obeys to the same physical law as the bulk Si crystal. In addition, the previously observed decrease of the PL intensity for decreasing temperatures is demonstrated to have its origin in the same measurement artifact caused by excitation saturation.
机译：自从第一个关于Si纳米晶体Si（NCs）的低温光致发光（PL）测量的报道以来，就报道了与通常用于描述块状材料的带隙能量的温度依赖性的方程式严重偏离的报道。我们的分析表明，以前观察到的偏差仅归因于太高的激发功率密度，由于辐射激子寿命的温度依赖性，太高的激发功率密度导致尺寸分布内较小NC的优先发射增强。我们报告了量子受限硅的温度相关带隙能量的成功拟合。通过使用四个尺寸受控的Si NC样品（1.5至4.5 nm），如果使用足够低的激发功率密度（<500μW/ cm〜2），我们能够证明这些方程在液氦温度下的有效性。 。从而表明，量子限制的纳米晶体Si的带隙扩展的特性服从与块状Si晶体相同的物理定律。此外，先前观察到的PL强度随温度降低的降低已证明其起源是由激发饱和引起的同一测量伪像。

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  • 来源
    《Physical review》 |2012年第16期|p.165306.1-165306.5|共5页
  • 作者

    A. M. Hartel; S. Gutsch; D. Hiller; M. Zacharias;

  • 作者单位

    IMTEK, Faculty of Engineering, Albert-Ludwigs-University Freiburg, Georges-Koehler-Allee 103, 79110 Freiburg, Germany;

    IMTEK, Faculty of Engineering, Albert-Ludwigs-University Freiburg, Georges-Koehler-Allee 103, 79110 Freiburg, Germany;

    IMTEK, Faculty of Engineering, Albert-Ludwigs-University Freiburg, Georges-Koehler-Allee 103, 79110 Freiburg, Germany;

    IMTEK, Faculty of Engineering, Albert-Ludwigs-University Freiburg, Georges-Koehler-Allee 103, 79110 Freiburg, Germany;

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  • 正文语种 eng
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  • 关键词

    nanocrystalline materials; nanocrystals and nanoparticles;

    机译：纳米晶体材料;纳米晶体和纳米颗粒;

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