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首页> 外文学位 >Electron transport in low dimensional gallium nitride/aluminum gallium nitride heterostructure.
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Electron transport in low dimensional gallium nitride/aluminum gallium nitride heterostructure.

机译：低维氮化镓/氮化铝镓异质结构中的电子传输。

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摘要

This thesis investigates electron transport in low dimensional GaN/AlGaN mesoscopic systems. Nanofabrication techniques give researchers the power to confine electrons in semiconductors to low dimensional mesoscopic systems. The host material can be so clean and electronically simple that we are not limited by the foibles of a particular material. Almost all interesting experiments on mesoscopic semiconductor have been based on GaAs/AlGaAs heterostructure because of the high quality of the material, and the fact that the electrons behave similarly to free electrons in vacuum except for modified physical parameters (effective electron mass and g-factor, etc.). Nonetheless, puzzles remain even for the simplest mesoscopic structures in GaAs.;By moving to a different material (GaN/AlGaN heterostructure), we can examine the universality of the observed behaviors of GaAs-based mesoscopic systems, and we can also probe how things change when we vary important parameters: GaN has a higher effective mass (3X) and lower dielectric constant (0.7X) than GaAs, making interactions more important relative to kinetic energy. GaN also has a higher g factor (4.5X), making it easier to control spin states by applying magnetic field. In this thesis I will present our results of transport measurement on two types of mesoscopic system based on GaN/AlGaN:;A quasi-1D system: Quantum Point Contacts (QPC) in GaN were fabricated and measured at low temperature. We observed well-quantized conductance plateaus, and the plateaus split into spin-resolved plateaus at high perpendicular magnetic field. We also observed features of 0.7 structure, an unresolved puzzle in GaAs QPCs.;A 0D system: Quantum Dots in GaN were fabricated and Coulomb blockade oscillations of conductance were observed at low temperature. The distribution of the spacing between consecutive Coulomb Blockade Peaks reveals the statistical properties of the level spacing of the confined electrons in the Quantum dot, which is predicted to have a variation close to mean level spacing. In previous experimental works on GaAs and Si dots, Gaussian distributions with a broad range of widths were observed. The observation of variation greater than mean level spacing in some GaAs and Si Quantum dot experiments has been attributed to the effect of strong electron-electron interactions. In the GaN dot we studied here, the electron-electron interactions are even stronger than in those previous experiments, yet we observed a Gaussian distribution of peak spacings with a width close to the mean level spacing, refuting the interpretation of broad variations in peak spacing in previous studies.
机译：本文研究了低维GaN / AlGaN介观体系中的电子传输。纳米制造技术使研究人员能够将半导体中的电子限制在低维介观系统中。主体材料可以如此干净和电子上简单，因此我们不受特定材料的缺点的限制。由于材料的高质量，几乎所有有趣的介观半导体实验都基于GaAs / AlGaAs异质结构，而且除了修改后的物理参数（有效电子质量和g因子）外，电子在真空中的行为与自由电子相似。等）。尽管如此，即使对于GaAs中最简单的介观结构，也仍然存在困惑;通过转移到不同的材料（GaN / AlGaN异质结构），我们可以检查基于GaAs的介观系统的观察到的行为的普遍性，并且我们还可以探究事物如何当我们改变重要参数时会发生变化：GaN比GaAs具有更高的有效质量（3X）和更低的介电常数（0.7X），从而使相互作用相对于动能更为重要。 GaN还具有较高的g因子（4.5X），从而更容易通过施加磁场来控制自旋状态。在这篇论文中，我将介绍我们在两种基于GaN / AlGaN的介观系统上的传输测量结果：准一维系统：制造并在低温下测量GaN中的量子点触点（QPC）。我们观察到了良好量化的电导高原，并且在高垂直磁场下，高原分裂成自旋分辨高原。我们还观察到0.7结构的特征，这在GaAs QPC中是一个未解决的难题。； 0D系统：在GaN中制造了量子点，并在低温下观察到电导的库仑阻塞振荡。连续的库仑封锁峰之间的间距分布揭示了量子点中受限电子的能级间距的统计特性，据预测，该变化具有接近平均能级间距的变化。在先前关于GaAs和Si点的实验工作中，观察到了宽范围的高斯分布。在某些GaAs和Si量子点实验中观察到的变化大于平均能级间距，这归因于强电子-电子相互作用的影响。在我们这里研究的GaN点中，电子-电子相互作用甚至比以前的实验更强，但是我们观察到了峰间距的高斯分布，其宽度接近于平均能级间距，从而驳斥了对峰间距宽泛变化的解释在以前的研究中。

著录项

  • 作者

    Chou, Hung-Tao.;

  • 作者单位

    Stanford University.;

  • 授予单位 Stanford University.;
  • 学科 Physics Condensed Matter.
  • 学位 Ph.D.
  • 年度 2009
  • 页码 95 p.
  • 总页数 95
  • 原文格式 PDF
  • 正文语种 eng
  • 中图分类 O49;
  • 关键词

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