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Kinetics of solid-solid phase transitions in semiconductor nanocrystals.

机译：半导体纳米晶体中固-固相变的动力学。

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摘要

Pressure-induced 4- to 6-coordinate phase transitions were investigated in both II-VI and III-V semiconductors as a function of crystallite size. The transition from the low pressure wurtzite phase to the high pressure rock salt phase in CdSe nanocrystals occurred with a distinct change in optical features, and rock salt CdSe was found to be an indirect gap semiconductor even in finite size. The change in optical features, combined with high pressure X-ray diffraction, was used to follow the phase transition kinetics of CdSe crystallites. CdSe nanocrystals transform from one structure to another by single nucleation events, and the transformations obey simple unimolecular kinetics. Barrier heights were observed to increase with increasing nanocrystal size. InP and InAs nanocrystals were also found to transform via single nucleation and have a larger range of metastability than the corresponding extended solids. The effects of consecutive pressure cycles on CdSe nanocrystals were investigated, and the transformation pressures and hysteresis were consistent on each iteration. The compressibility of InP nanocrystals and CdSe nanocrystals were compared to the respective bulk semiconductors, and the observed deviations from the bulk were examined in relation to the quality of the surrounding pressure medium.
机译：在II-VI和III-V半导体中都研究了压力诱导的4至6坐标相变与微晶尺寸的关系。在CdSe纳米晶体中，从低压纤锌矿相到高压岩盐相的转变发生了光学特征的明显变化，并且发现岩盐CdSe甚至是有限尺寸的间接间隙半导体。光学特征的变化与高压X射线衍射相结合，用于追踪CdSe晶体的相变动力学。 CdSe纳米晶体通过单个成核事件从一种结构转变为另一种结构，并且该转变遵循简单的单分子动力学。观察到势垒高度随着纳米晶体尺寸的增加而增加。还发现InP和InAs纳米晶体通过单核化而发生转变，并且比相应的扩展固体具有更大的亚稳范围。研究了连续压力循环对CdSe纳米晶体的影响，并且每次迭代的相变压力和磁滞都一致。将InP纳米晶体和CdSe纳米晶体的可压缩性与各自的块状半导体进行了比较，并检查了与块状相对于周围压力介质质量的偏差。

著录项

  • 作者

    Herhold, Amy Bowen.;

  • 作者单位

    University of California, Berkeley.;

  • 授予单位 University of California, Berkeley.;
  • 学科 Chemistry Physical.; Physics Condensed Matter.
  • 学位 Ph.D.
  • 年度 1997
  • 页码 137 p.
  • 总页数 137
  • 原文格式 PDF
  • 正文语种 eng
  • 中图分类 物理化学（理论化学）、化学物理学;
  • 关键词

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