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A fundamental study of silicon nanocrystals derived from hydrogen silsesquioxane.

机译：对氢倍半硅氧烷衍生的硅纳米晶体的基础研究。

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摘要

A novel synthesis for gram quantities of luminescent, oxide-embedded and freestanding silicon nanocrystals is presented. The reductive thermal processing of hydrogen silsesquioxane (HSQ) yields size-controlled oxide-embedded silicon nanocrystals, and their subsequent liberation through straight-forward hydrofluoric (HF) acid etching procedures allows tailoring of their optical response throughout the visible region of the electromagnetic spectrum.;The thermally-induced transformation of HSQ to oxide-embedded silicon nanocrystals occurs via a multi-step process, involving cage rearrangement, network decomposition to form silane-like species, in-situ silane decomposition to form elemental silicon clusters, and subsequent nucleation, growth and crystallization to form silicon nanocrystals in an SiO2 matrix. This formation process was confirmed using detailed spectroscopic and microscopic characterization.;The luminescence characteristics of oxide-embedded and freestanding silicon nanocrystals were determined using laser-based photoluminescence and X-ray excited optical luminescence spectroscopy. Oxide-embedded systems were found to exhibit two emission bands in the visible region of the electromagnetic spectrum: a high energy emission that is independent of nanocrystal size, and a size-dependent low energy emission. HF etching was employed to liberate the silicon nanocrystals from the encapsulating oxide in order to assign the origin of these emission bands. Oxide removal was accompanied by a loss of the green emission, indicating that it is of silicon oxide origin. Progressively decreasing the nanocrystal size with extended HF treatment was accompanied by a blue-shift in the emission energy and a narrowing of the emission profile, indicative of an increase in the bandgap energy and a narrowing of the density of states, respectively. This behavior establishes that the low energy emission band is a result of quantum confinement effects in sub-5nm silicon nanocrystals.;It was found that HSQ is an ideal precursor for conformal coating of both flat and not-flat surfaces with oxide-embedded silicon nanocrystals, highlighting its device application potential. Patterning of luminescent sub-10 nm structures was also achieved by electron beam writing and subsequent thermal processing.;The ability to produce large quantities of size-controlled oxide-embedded and freestanding silicon nanocrystals in bulk and thin film architectures demonstrates that HSQ is currently the most versatile silicon nanocrystal precursor available.
机译：提出了一种新颖的合成方法，用于合成克量的发光，氧化物嵌入和独立式硅纳米晶体。氢倍半硅氧烷（HSQ）的还原热处理产生尺寸可控的氧化物包埋的硅纳米晶体，其随后通过直接氢氟酸（HF）酸蚀刻程序的释放允许在电磁光谱的整个可见区域内调整其光学响应。 ； HSQ的热诱导转变为氧化物嵌入的硅纳米晶体是通过多步过程进行的，包括笼子重排，网络分解以形成硅烷样物质，原位硅烷分解以形成元素硅簇以及随后的成核，生长和结晶以在SiO2基质中形成硅纳米晶体。通过详细的光谱学和显微表征证实了该形成过程。使用激光基光致发光和X射线激发光致发光光谱法确定了氧化物包埋的和独立的硅纳米晶体的发光特性。发现嵌入氧化物的系统在电磁波谱的可见光区域显示两个发射带：与纳米晶体尺寸无关的高能发射和与尺寸有关的低能量发射。为了指定这些发射带的起源，采用HF蚀刻从封装氧化物中释放出硅纳米晶体。氧化物的去除伴随着绿色发射的损失，表明它是氧化硅来源。随着延长的HF处理而逐渐减小纳米晶体的尺寸，伴随着发射能量的蓝移和发射轮廓的变窄，分别指示带隙能量的增加和态密度的变窄。这种行为表明低能发射带是亚5nm纳米硅纳米晶体中量子限制效应的结果;发现HSQ是用氧化物嵌入的硅纳米晶体共形涂覆平坦和非平坦表面的理想前体，突出其设备的应用潜力。通过电子束写入和随后的热处理也可以实现10nm以下发光结构的图案化。在体和薄膜结构中能够生产大量尺寸受控的氧化物嵌入和独立式硅纳米晶体的能力表明，HSQ是目前的最通用的硅纳米晶体前体。

著录项

  • 作者

    Hessel, Colin M.;

  • 作者单位

    University of Alberta (Canada).;

  • 授予单位 University of Alberta (Canada).;
  • 学科 Chemistry Inorganic.
  • 学位 Ph.D.
  • 年度 2008
  • 页码 149 p.
  • 总页数 149
  • 原文格式 PDF
  • 正文语种 eng
  • 中图分类 无机化学;
  • 关键词

  • 入库时间 2022-08-17 11:38:41

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