• 主题
高级搜索  >
历史搜索 清空历史
首页> 外文学位 >High efficiency III-nitrides-based UV/deep-UV light emitting devices of micro/nano-photonic structures.
【24h】

High efficiency III-nitrides-based UV/deep-UV light emitting devices of micro/nano-photonic structures.

机译：微/纳米光子结构的高效基于III族氮化物的UV / Deep-UV发光器件。

获取原文
获取原文并翻译 | 示例
页面导航
  • 摘要
  • 著录项
  • 相似文献
  • 相关主题

摘要

The frontiers of micro/nano photonic structures based light emitting device research spans a variety of III-nitride wide-bandgap semiconductors to achieve high efficiencies. The development of compact, robust, milliwatt-level LEDs that emit in ultraviolet (UV) and deep-ultraviolet (deep-UV) would greatly impact a number of applications from fluorescence-based biological agent detection to solid-state lighting. Continued research on the improvement of high efficiency short wavelength post-epi device fabrication procedures is one of high priorities.;This dissertation focuses on the understanding, design optimization, post-epi advance processing, flip chip packaging, and characterization of several key aspects of micro/nano photonic structures for UV/deep-UV light emitting devices. From the studies of AlInGaN-based UV LEDs epi-structures, we found that the high dislocation densities severely reduce emission efficiency. Therefore, reduced defect density substrates or nucleation process is key to realizing high brightness devices. For deep-UV LEDs (&lgr;∼300 nm), our focus has been to understand the physical phenomena and properties that dominate as the device size scales down. We concluded that the compact-size light sources offer benefits over lateral-geometry emitters. Device size dependence study showed that the circular disk and interdigitated LEDs design have been very effective to overcome current crowding and current spreading issues. Through a comparative study of various disk sizes, we found that the power density of the small sized ∼275 mum disk LEDs is optimal and can be considered ideal for high power compact UV/deep-UV LEDs. The dry plasma treatment damage in p-AlGaN/GaN was studied systematically using Schottky diode measurements. Various devices, including individual lateral geometry, hexagonal geometry, circular disk and interdigitated with varying mesa sizes (85 mum to 1 mm 2) were investigated. Monolithically integrated micro/nano structures, such as, microlens, photonic crystals and Fresnel lenses were also processed.;Based on the latest technical improvements, local thermal management (ILTM) of flip-chip packaged UV/deep-UV LEDs were explored for high efficiency. Contrary to conventional electroplating technique, void free bumps with better surface morphology were used with sputter-coating technology. The devices processed with ILTM techniques were thermally more stable, attributed to the unique metallurgical properties. With the L-I-V characterization of the processed devices, an enhanced optical power of 0.25 mW at 20 mA was obtained. Finally, the effect of multilayer's materials annealing, substrate surface nano-pattering/roughening, reflection multilayers and the packaging of the devices was also studied for the high efficiency of UV/deep-UV LEDs. After a careful optimization of post-epi processes individually, light emitting devices were fabricated in a single process flow. After performing a series of control experiments, we found that a modified metallization scheme such as Al/Ti/Au on bi-layer Ni/Au p-contacts could be a viable option for a stable reflection layer. An ILTM for the flip-chip devices (FCLEDs) were employed. With the comparison of conventional to FCLEDs, an output power of 0.45 mW with a forward voltage of 6.7 V at 20 mA was achieved. The thermal stability of these devices is far better compared to conventional packaged devices. Optoelectronic characterization of these devices suggested that UV/deep-UV light emitting device's life time has significantly improved with overall efficiency.
机译：基于微/纳米光子结构的发光器件研究的前沿领域跨越了多种III型氮化物宽带隙半导体，以实现高效率。能够发射紫外线（UV）和深紫外线（deep-UV）的紧凑，坚固，毫瓦级LED的发展将极大地影响从基于荧光的生物制剂检测到固态照明的许多应用。继续研究改进短波高效短波器件的制造工艺是当务之急。;本论文着重于对以下方面的理解，设计优化，后波普先进工艺，倒装芯片封装以及特性表征。用于紫外/深紫外发光器件的微米/纳米光子结构。通过对基于AlInGaN的UV LED外延结构的研究，我们发现高位错密度严重降低了发射效率。因此，减少缺陷密度的基板或成核工艺是实现高亮度器件的关键。对于深紫外LED（〜300 nm），我们的重点是了解随着器件尺寸缩小而占主导地位的物理现象和特性。我们得出的结论是，紧凑尺寸的光源比横向几何形状的发射器更具优势。器件尺寸依赖性研究表明，圆盘和叉指式LED设计对于克服电流拥挤和电流扩散问题非常有效。通过对各种磁盘尺寸的比较研究，我们发现小尺寸〜275毫米磁盘LED的功率密度是最佳的，可以认为是大功率紧凑型UV /深紫外LED的理想选择。使用肖特基二极管测量系统地研究了p-AlGaN / GaN中的干法等离子体处理损伤。研究了各种装置，包括单个的横向几何形状，六边形几何形状，圆盘以及具有不同台面尺寸（85毫米至1毫米2）的叉指。还处理了单片集成的微/纳米结构，例如微透镜，光子晶体和菲涅耳透镜。;基于最新的技术改进，对倒装芯片封装的UV / Deep-UV LED的局部热管理（ILTM）进行了探索，以实现更高的发光效率。效率。与传统的电镀技术相反，溅射镀膜技术使用了具有更好表面形态的无空凸点。使用ILTM技术处理的设备在热方面更稳定，这归因于其独特的冶金性能。通过对被处理器件进行L-I-V表征，可获得20 mA时0.25 mW的增强光功率。最后，还研究了多层材料退火，基板表面纳米图案化/粗糙化，反射多层和器件封装的效果，以实现紫外/深紫外LED的高效率。在分别仔细地优化了上表后工艺之后，以单个工艺流程制造了发光器件。在执行一系列控制实验后，我们发现，在双层Ni / Au p触点上采用改进的金属化方案（例如Al / Ti / Au）可能是稳定反射层的可行选择。采用了用于倒装芯片器件（FCLED）的ILTM。通过与传统LED和FCLED的比较，在20 mA时实现了0.45 mW的输出功率和6.7 V的正向电压。与传统的封装设备相比，这些设备的热稳定性要好得多。这些器件的光电特性表明，UV /深紫外发光器件的使用寿命随着整体效率得到了显着改善。

著录项

  • 作者

    Khizar, Muhammad.;

  • 作者单位

    The University of North Carolina at Charlotte.;

  • 授予单位 The University of North Carolina at Charlotte.;
  • 学科 Engineering Electronics and Electrical.;Engineering Materials Science.;Energy.
  • 学位 Ph.D.
  • 年度 2008
  • 页码 181 p.
  • 总页数 181
  • 原文格式 PDF
  • 正文语种 eng
  • 中图分类
  • 关键词

相似文献

  • 外文文献
  • 中文文献
  • 专利
获取原文

客服邮箱：kefu@zhangqiaokeyan.com

京公网安备：11010802029741号 ICP备案号：京ICP备15016152号-6 六维联合信息科技 (北京) 有限公司©版权所有

  • 客服微信

  • 服务号