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White light-emitting diodes based on nonpolar and semipolar gallium nitride orientations.

机译：基于非极性和半极性氮化镓取向的白色发光二极管。

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摘要

Gallium nitride has become one of the key components when fabricating white light-emitting diodes. Its use as the blue source in conjunction with a wavelength converter such as the yellow emitting phosphor YAG:Ce 3+ is a technology that is commercially available and usable for solid state lighting applications. Currently available white phosphor-based LEDs (pcLEDs) use the basal plane of wurtzite GaN as their source. Although research over the past couple decades has developed this technology into devices with good photometric performance and high reliability, the introduction of nonbasal plane wurtzite GaN orientations have benefits over basal plane GaN that can be incorporated into the white LED.;The focus of this research deals with exploring white illumination on nonpolar and semipolar planes of GaN. Light extraction techniques will be described that allowed for high output powers and efficiencies on the c-plane as well as the (1100), (10 11), and (1122) planes of GaN. With higher performing devices, white pcLEDs were fabricated on c-plane, m-plane, and the (1011) semipolar plane.;The novelty in the present research is producing white LEDs with nonbasal plane diodes which exhibit optical polarization anisotropy. This feature, absent on the basal plane, allows for tuning photometric quantities both electrically and optically. This is demonstrated on pcLEDs as well as dichromatic LEDs comprised solely of InGaN diodes. As a consequence of these measurements, an apparent optical polarization was seen to be occurring in the luminescence of the YAG:Ce3+ when the system absorbed linearly polarized light.;Polarized emission in YAG:Ce3+ was explored by obtaining single crystals of YAG:Ce3+ with different planar orientations. The experiments led to the conclusion that crystal orientation plays no part in the optical polarization. It is suggested that the cause is a result of electric dipole transitions given by various selection rules between the Ce 3+ ion's 4f and 5d orbitals. It was also possible to obtain white illumination at several current values using the single crystal and a GaN source. Features of the photoluminescence show the allowed quantum transitions of YAG:Ce3+ prominently.
机译：氮化镓已成为制造白色发光二极管时的关键组件之一。它与波长转换器（例如发射黄色荧光粉YAG：Ce 3+）一起用作蓝色光源，是一项可商购的技术，可用于固态照明应用。当前可用的基于白色磷光体的LED（pcLED）使用纤锌矿GaN的基面作为其源。尽管过去几十年的研究已将该技术开发为具有良好光度性能和高可靠性的设备，但非基面纤锌矿GaN取向的引入比可并入白光LED的基面GaN更具优势。涉及探索GaN非极性和半极性平面上的白色照明。将描述允许在c平面以及GaN的（1100），（10 11）和（1122）平面上具有高输出功率和效率的光提取技术。使用性能更高的器件，可在c平面，m平面和（1011）半极性平面上制造白色pcLED。本研究的新颖之处在于生产具有非基面二极管且显示光学偏振各向异性的白色LED。在基面上不存在的此功能允许通过电和光学方式调整光度数量。这在pcLED以及仅由InGaN二极管组成的二色LED中得到了证明。这些测量的结果是，当系统吸收线性偏振光时，在YAG：Ce3 +的发光中看到了明显的光学偏振。;通过获得YAG：Ce3 +的单晶，探索了YAG：Ce3 +中的极化发射。不同的平面方向。实验得出的结论是晶体取向在光学偏振中不起作用。建议原因是Ce 3+离子的4f和5d轨道之间通过各种选择规则给出的电偶极跃迁的结果。使用单晶和GaN源，还可以在几个电流值下获得白色照明。光致发光的特征突出显示了YAG：Ce3 +的允许量子跃迁。

著录项

  • 作者

    DeMille, Natalie Fellows.;

  • 作者单位

    University of California, Santa Barbara.;

  • 授予单位 University of California, Santa Barbara.;
  • 学科 Engineering Materials Science.
  • 学位 Ph.D.
  • 年度 2009
  • 页码 201 p.
  • 总页数 201
  • 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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