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The assessment of emission mechanism in GaN-based nano-structures by scanning near-field optical microscopy

通过扫描近场光学显微镜评估 GaN 基纳米结构的发射机制

基本信息

批准号：
15206033
负责人：
KAWAKAMI Yoichi
金额：
$ 25.79万
依托单位：
Kyoto University
依托单位国家：
日本
项目类别：
Grant-in-Aid for Scientific Research (A)
财政年份：
2003
资助国家：
日本
起止时间：
2003 至 2005
项目状态：
已结题

项目摘要

The purpose of this project is to assess and/or control the radiative recombination processes in InGaN/GaN-based quantum wells by employing photoluminescence (PL) mapping with scanning near field optical microscopy (SNOM), by which dramatic improvement of emission efficiency as well as the extension of operatable wavelength can be achieved in emitters such as light emitting diodes (LEDs), laser diodes (LDs) and new phosphors. Our approach is to fabricate micro/nano structures for multi-wavelength lighting, to elucidate fundamental optical properties, and to make a positive feedback to future device structures. Main results are summarized as shown below.(1)We have developed the experimental technique by combining the SNOM-PL with atomic force microscopy (AFM), where the correlation was clearly revealed between dislocations and weak emission regions. Moreover, time-resolved PL measurements with this method showed the dynamical behavior of photo-generated carriers and/or excitons in potential fluctuations. It was found that the pathway to nonradiative recombination centers is effectively hindered by the compositional modulation around the dislocations, so that the carrier diffusion is spatially unisotropic process.(2)We have proposed the re-growth technique, where well-established c-oriented GaN is used as a seed. It has been demonstrated that the growth on c-oriented GaN patterned with a stripe along the [11^^-00] direction forms (0001), <112^^-2>, and <112^^-0> facets and that the QW on the <112^^-2> facet involves weaker electric fields and has a higher PL efficiency, compared with conventional c-oriented InGaN/GaN QWs. Moreover, rainbow color PL covering the entire visible range has been achieved from InGaN/GaN QWs on the <112^^-2> facets with a few micron-width.

本研究的目的是通过扫描近场光学显微镜（SNOM）的光致发光（PL）成像技术来评估和/或控制InGaN/GaN基量子威尔斯中的辐射复合过程，从而显著提高发光二极管（LED）、激光二极管（LD）和新型荧光粉等发光器件的发光效率并扩展其工作波长。我们的方法是制造多波长照明的微/纳米结构，阐明基本的光学特性，并对未来的器件结构做出积极的反馈。主要结果总结如下。(1)We已经开发了实验技术相结合的SNOM-PL与原子力显微镜（AFM），其中的相关性清楚地揭示了位错和弱发射区之间。此外，时间分辨的PL测量与这种方法显示光生载流子和/或激子的动态行为的潜在波动。结果表明，位错周围的成分调制有效地阻碍了载流子向非辐射复合中心的扩散，使载流子扩散成为空间各向异性的过程。(2)We已经提出了再生长技术，其中使用公认的c取向GaN作为种子。已经证明，在c取向GaN上以沿[11^^-00]方向沿着的条带图案化的生长形成（0001）、<112^^-2>和<112^^-0>面，并且与常规c取向InGaN/GaN QW相比，在<112^^-2>面上的QW涉及较弱的电场并且具有较高的PL效率。此外，InGaN/GaN量子阱在<112^^-2>面上实现了几微米宽的彩虹色PL，覆盖了整个可见光范围。