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Magnetotransport study of a high mobility two-dimensional electron gas.

机译：高迁移率二维电子气的磁输运研究。

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摘要

This thesis is focused on an experimental study of the electrical properties of a two-dimensional electron gas formed in a GaAs/AlGaAs heterostructure. Low temperature magneto-transport measurements are used to characterize the carrier density and mobility of this system. An extensive study of the temperature and current dependence of quantum-mechanical transport effects, observable at very low temperatures, is performed in the temperature range of 4.2-100 K, for measurement currents in the range of 10 nA- 100muA. The well-known decrease in the amplitude of the Shubnikov-de Haas effect, and an accompanying increase in the onset magnetic field of these oscillations, with increasing temperature, as well as a simultaneous suppression of the quantum-Hall effect, is observed. Similar behavior is found on increasing the measurement current. An analysis of the insulator to quantum Hall transition (I-QH), occurring in the two-dimensional electron gas at low perpendicular magnetic fields, is also reported, along with the results of investigations of electron heating based on the measurements of the energy-loss rate. This study shows that the direct I-QH transition does not always correspond to the onset of strong localization, with clear Shubnikov-de Haas oscillations being observed in the insulating regime. A linear dependence of the electron energy-loss rate and electron temperature in the temperature range of 4.2-40 K is determined, indicating that the main mechanism for electron energy relaxation is acoustic phonon scattering.
机译：本文的重点是在GaAs / AlGaAs异质结构中形成的二维电子气的电学特性的实验研究。低温磁传输测量用于表征该系统的载流子密度和迁移率。在4.2-100 K的温度范围内进行了对量子力学传输效应的温度和电流相关性的广泛研究（可在非常低的温度下观察到），测量电流范围为10 nA-100muA。观察到众所周知的是，Shubnikov-de Haas效应的幅度减小，并且随着温度升高，这些振荡的起始磁场随之增加，并且同时抑制了量子霍尔效应。在增加测量电流时发现类似的行为。还报告了在低垂直磁场下二维电子气中发生的绝缘体到量子霍尔跃迁（I-QH）的分析，以及基于能量测量的电子加热研究结果。损失率。这项研究表明，直接的I-QH跃迁并不总是与强定位的开始相对应，在绝缘状态下观察到了清晰的Shubnikov-de Haas振荡。在4.2-40 K的温度范围内，电子能量损失率与电子温度之间存在线性关系，这表明电子能量弛豫的主要机理是声子声子散射。

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  • 作者

    Bohra, Girish.;

  • 作者单位

    State University of New York at Buffalo.;

  • 授予单位 State University of New York at Buffalo.;
  • 学科 Engineering Electronics and Electrical.;Physics General.;Physics Condensed Matter.
  • 学位 M.S.
  • 年度 2009
  • 页码 71 p.
  • 总页数 71
  • 原文格式 PDF
  • 正文语种 eng
  • 中图分类 无线电电子学、电信技术;物理学;
  • 关键词

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