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Investigation of doped zinc oxide by molecular beam epitaxy for n- and p-type Conductivity.

机译：通过分子束外延研究掺杂的氧化锌的n型和p型电导率。

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摘要

This dissertation presents an investigation of the properties, especially the electrical properties, of doped ZnO films grown by plasma-assisted molecular beam epitaxy (MBE) under different conditions. The interest in investigating ZnO films is motivated by the potential of ZnO to replace the currently dominant ITO in industries as n-type transparent electrodes and the difficulty in achieving reliable and reproducible p-type ZnO. On the one hand, n-type ZnO heavily doped with Al or Ga (AZO or GZO) is the most promising to replace ITO due to the low cost, abundant material resources, non-toxicity , high conductivity, and high transparency. On the other hand, ZnO doped with a large-size-mismatched element of Sb (SZO) or co-doped with N and Te exhibits the possibility of achieving p-type ZnO.;In this dissertation, the effects of MBE growth parameters on the properties of GZO have been investigated in detail. The ratio of oxygen to metal (Zn+Ga) was found to be critical in affecting the structural, electrical, and optical properties of GZO layers as revealed by x-ray diffraction (XRD), transmission electron microscopy (TEM), Hall measurement, photoluminescence (PL), and transmittance measurements. Highly conductive (∼2×10-4 Ω-cm) and transparent GZO films (> 90% in the visible spectral range) were achieved by MBE under metal-rich conditions (reactive oxygen to incorporated Zn ratio < 1). The highly conductive and transparent GZO layers grown under optimized conditions were applied as p-side transparent electrodes in InGaN-LEDs, which exhibited many advantages over the traditional thin semi-transparent Ni/Au electrodes. The surface morphologies of GaN templates were demonstrated to be important in affecting the structural and electrical properties of GZO layers. In those highly conductive and transparent GZO layers with high-quality crystalline structures, studies revealed ionized impurity scattering being the dominant mechanism limiting the mobility in the temperature range of 15-330 K, while polar optical phonon scattering being the mechanism responsible for the temperature-dependence for T>150 K. The majority Sb ions were found to reside on Zn sites instead of O sites for lower Sb concentrations (∼0.1 at.%), which can lead to a high electron concentration of above 10 19 cm-3 along with a high electron mobility of 110 cm2/V-s at room temperature. The reduction in electron concentration and mobility for higher Sb concentrations (∼1 at.%) was caused by the deterioration of the crystalline quality. ZnO co-doped with N and Te was also studied and the advantages of the co-doping technique and problems in achieving p-type conductivity are discussed.
机译：本文研究了在不同条件下通过等离子体辅助分子束外延生长的掺杂ZnO薄膜的性能，特别是电学性能。研究ZnO膜的兴趣是由ZnO替代工业中目前占主导地位的ITO（作为n型透明电极）的潜力以及难以获得可靠且可再现的p型ZnO引起的。一方面，由于其低成本，丰富的材料资源，无毒，高电导率和高透明度，重掺杂Al或Ga的n型ZnO（AZO或GZO）是最有希望替代ITO的材料。另一方面，掺杂有大尺寸不匹配元素Sb（SZO）或掺有N和Te的ZnO具有实现p型ZnO的可能性。对GZO的特性进行了详细的研究。发现氧与金属的比率（Zn + Ga）对于影响GZO层的结构，电学和光学性质至关重要，这可以通过X射线衍射（XRD），透射电子显微镜（TEM），霍尔测量，光致发光（PL）和透射率测量。 MBE在富含金属的条件下（活性氧与掺入的Zn之比<1）实现了高导电性（〜2×10-4Ω-cm）和透明GZO膜（在可见光谱范围内> 90％）。在优化条件下生长的高导电性和透明GZO层被用作InGaN-LED中的p侧透明电极，与传统的薄半透明Ni / Au电极相比，具有许多优势。事实证明，GaN模板的表面形态对于影响GZO层的结构和电学性能至关重要。在那些具有高质量晶体结构的高导电性和透明GZO层中，研究表明，电离杂质散射是限制15-330 K温度范围内迁移率的主要机制，而极性光学声子散射是造成温度升高的机制。依赖于T> 150K。对于较低的Sb浓度（〜0.1 at。％），发现大多数Sb离子驻留在Zn位置而不是O位置，这可能导致沿10 19 cm-3以上的高电子浓度在室温下具有110 cm2 / Vs的高电子迁移率。对于较高的Sb浓度（〜1 at。％），电子浓度和迁移率的降低是由于晶体质量的下降引起的。还研究了N和Te共掺杂的ZnO，并讨论了共掺杂技术的优势以及实现p型导电性的问题。

著录项

  • 作者

    Liu, Huiyong.;

  • 作者单位

    Virginia Commonwealth University.;

  • 授予单位 Virginia Commonwealth University.;
  • 学科 Engineering Electronics and Electrical.;Engineering Materials Science.
  • 学位 Ph.D.
  • 年度 2012
  • 页码 170 p.
  • 总页数 170
  • 原文格式 PDF
  • 正文语种 eng
  • 中图分类
  • 关键词

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