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Nanometer-scale studies of interdiffusion and segregation in semiconductor structures.

机译：半导体结构相互扩散和隔离的纳米尺度研究。

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摘要

Interdiffusion and segregation are fundamental processes that lead to changes in structural and compositional uniformity of heterostructures, which in turn affect the performance of electronic and photonic devices. As devices are continually reduced in size, the distribution of the chemical species near heterointerfaces, often determined by the interdiffusion and segregation processes, becomes of crucial importance. In this dissertation, a combination of cross-sectional scanning tunneling microscopy and spectroscopy, cross-sectional transmission electron microscopy, and high-resolution x-ray diffraction has been employed to investigate the interdiffusion and segregation processes in molecular-beam-epitaxially-grown heterostructures. This work provides insight into these processes, including direct measurements of the interdiffusion and segregation lengths, on an atomic scale. The effects of residual strain on these fundamental parameters are also discussed.; In the non-stoichiometric AlAs/GaAs superlattices, results suggest that Al-Ga interdiffusion induces an apparent superlattice disordering. In addition, misfit strain presumably affects the preferential As precipitation along the GaAs side of each AlAs/GaAs interface. The preferential As precipitation, less apparent after ex situ annealing, may be diminished by Al-Ga interdiffusion at the AlAs/GaAs interfaces.; In the ZnSnP2/GaAs superlattices, an asymmetry in interface abruptness is observed, with the GaAs on ZnSnP2 interfaces apparently much smoother than the ZnSnP2 on GaAs interfaces. This asymmetry is likely due to strain-enhanced surface segregation of Sn occurring during the growth of GaAs on ZnSnP2. Furthermore, the ZnSnP2 layers appear inhomogeneous, due to compositional fluctuations caused by the presence of ZnSnP2 and ZnSnAs2-rich regions.; Investigations of in situ and ex situ post-growth thermal annealing of InAs/GaAs quantum dot superlattices suggest that the organization of these superlattices is affected by annealing-induced dot dissolution. Annealing-induced variations in the positions of the In atoms between the dot arrays enable direct measurements of In-Ga interdiffusion and In segregation lengths. Finally, the effects of residual strain on the dissolution of dots in dot arrays are discussed.
机译：互扩散和隔离是导致异质结构的结构和组成均匀性发生变化的基本过程，继而影响电子和光子器件的性能。随着装置尺寸的不断减小，异质界面附近化学物种的分布（通常由相互扩散和隔离过程决定）变得至关重要。本文采用截面扫描隧道显微镜和光谱学，截面透射电子显微镜和高分辨率X射线衍射相结合的方法研究分子束外延生长的异质结构中的互扩散和偏析过程。 。这项工作提供了对这些过程的深入了解，包括在原子尺度上直接测量相互扩散和偏析的长度。还讨论了残余应变对这些基本参数的影响。在非化学计量的AlAs / GaAs超晶格中，结果表明Al-Ga互扩散引起明显的超晶格无序。此外，失配应变可能会影响沿每个AlAs / GaAs界面的GaAs侧的优先As析出。在AlAs / GaAs界面处的Al-Ga互扩散可以减少在非原位退火后不太明显的优先As沉淀。在ZnSnP 2 / GaAs超晶格中，观察到界面突变的不对称性，ZnSnP 2 界面上的GaAs明显比ZnSnP 2 光滑。 >在GaAs接口上。这种不对称性可能是由于GaS在ZnSnP 2 上生长期间发生的Sn的应变增强表面偏析。此外，由于存在富含ZnSnP 2 和富含ZnSnAs 2 的区域引起的成分波动，ZnSnP 2 层显得不均匀。 InAs / GaAs量子点超晶格的原位和 exsitu 生长后热退火的研究表明，这些超晶格的组织受到退火诱导的点溶解的影响。退火引起的点阵之间In原子位置的变化使得能够直接测量In-Ga互扩散和In隔离长度。最后，讨论了残余应变对点阵列中点溶解的影响。

著录项

  • 作者

    Lita, Bogdan.;

  • 作者单位

    University of Michigan.;

  • 授予单位 University of Michigan.;
  • 学科 Engineering Materials Science.; Physics Condensed Matter.
  • 学位 Ph.D.
  • 年度 2002
  • 页码 202 p.
  • 总页数 202
  • 原文格式 PDF
  • 正文语种 eng
  • 中图分类 工程材料学;
  • 关键词

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