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首页> 外文会议>State-of-the-art program on compound semiconductors 58 >Terahertz Spectroscopy: Studying Carrier Dynamics in Semiconductor Nanostructures
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Terahertz Spectroscopy: Studying Carrier Dynamics in Semiconductor Nanostructures

机译：太赫兹光谱：研究半导体纳米结构中的载流子动力学

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摘要

Understanding the ultrafast dynamics of photoexcited carriers in semiconductor nanostructures and their dependence on sample morphology is crucial for their incorporation into photonic devices. Time-resolved terahertz (THz) spectroscopy (TRTS) is an all-optical, contact-free technique that directly measures the transient mobile carrier dynamics and terahertz conductivity in materials over picosecond time scales, and is uniquely suited as a probe of conductivity in nanomaterials. Using low temperature MBE-grown silicon films as an example, we show how TRTS can be used to probe microscopic photoconductivity as well as obtain crucial insights into sample morphology. The thin silicon films consist of a mixture of amorphous and crystalline phases, and their relative content changes drastically with growth temperature. Photoexcited carrier dynamics in these films are determined by film crystallinity: in the amorphous phase, carriers are trapped in bandtail states on sub-picosecond time scales, while the carriers excited in crystalline grains remain free for tens of picoseconds. The complex THz conductivity spectra obtained from the TRTS measurements show that the long range conductivity is significantly higher in films grown at higher temperatures that contain a larger fraction of crystalline material with larger crystal grain sizes.
机译：了解半导体纳米结构中光激发载流子的超快速动力学及其对样品形态的依赖性对于将其掺入光子器件至关重要。时间分辨太赫兹（THz）光谱（TRTS）是一种全光学，无接触技术，可直接在皮秒级的时间范围内测量材料中的瞬态移动载流子动力学和太赫兹电导率，特别适合用作纳米材料中电导率的探针。以低温MBE生长的硅膜为例，我们展示了TRTS如何可用于探测微观光电导性以及获得对样品形态的关键见解。硅薄膜由非晶相和结晶相的混合物组成，它们的相对含量随生长温度而急剧变化。这些薄膜中受光激发的载流子动力学取决于薄膜的结晶度：在非晶相中，载流子在亚皮秒级的时间内被带状捕获，而在晶粒中激发的载流子则保持数十皮秒的自由状态。从TRTS测量获得的复数THz电导率谱表明，在较高温度下生长的薄膜中，长程电导率明显更高，该薄膜包含较大比例的晶体材料和较大的晶粒尺寸。

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  • 会议地点 Phoenix AZ(US)
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    Lyubov V. Titova; Sijia Xu; Jean-Marc Baribeau; David J. Lockwood; Frank A. Hegmann;

  • 作者单位

    Department of Physics, Worcester Polytechnic Institute, Worcester, MA 01609, USA,Department of Physics, University of Alberta, Edmonton, Alberta T6G 2E1, Canada;

    Department of Physics, University of Alberta, Edmonton, Alberta T6G 2E1, Canada;

    National Research Council, Ottawa, ON K1A 0R6, Canada;

    National Research Council, Ottawa, ON K1A 0R6, Canada;

    Department of Physics, University of Alberta, Edmonton, Alberta T6G 2E1, Canada;

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