Study on nonradiative recombination mechanism in widegap semiconductors

宽禁带半导体非辐射复合机理研究

基本信息

批准号：
12450011
负责人：
KAWAKAMI Yoichi
金额：
$ 8.7万
依托单位：
KYOTO UNIVERSITY
依托单位国家：
日本
项目类别：
Grant-in-Aid for Scientific Research (B)
财政年份：
2000
资助国家：
日本
起止时间：
2000 至 2002
项目状态：
已结题

项目摘要

The purpose of this work is to (1) characterize quantitatively the dynamics of capture processes of excitons and/or carriers injected to active layers in widegap semiconductors, (2) clarify the atomic nature of nonradiative recombination centers and correlate with their electronic states, and (3) develop an atomically controlled growth technology by making positive feedback to the growth conditions taking into account the data obtained at (1) and (2). Many of photo-generated and/or electrically injected excitons/carriers looses their energy by the nonradiative recombination processes. Therefore, the elimination as well as the assessment of such mechanism would lead to the improvement of emission efficiency.In this research project, we have succeeded in the observation of radiation-less processes related to carrier diffusion, and heat generation and diffusion due to nonradiative recombination, by employing transient grating spectroscopy based on third order optical nonlinearity. So far, such observation was difficult in spite of its importance.Moreover, we have developed microscopic heat-detecting spectroscopy by combining transient lens spectroscopy with optical microscopy, by which spatial and temporal measurement of the photo-thermal process was assessed at GaN epilayers with low dislocation density, and generation and diffusion of the heat originating from nonradiative recombination could be estimated quantitatively with a spatial resolution of 3 μm. As a result, it was confirmed that threading dislocations act as nonradiative recombination centers of excitons just after photo-generation.Furthermore, we have set up a scanning near-field optical microscopy, by using an apparatus which is capable of detecting both radiative and nonradiative recombination processes complimentary. We expect the future development of the research because of the improvement of spatial resolution down to from sum-micron to nanoscopic level.

The purpose of this work is to (1) characterize quantitatively the dynamics of capture processes of excitons and/or carriers injected to active layers in widegap semiconductors, (2) clarify the atomic nature of nonradiative recombination centers and correlate with their electronic states, and (3) develop an atomically controlled growth technology by making positive feedback to the growth conditions taking into account the data obtained at (1) and (2).许多照片生成和/或电去注射的激子/携带者因非辐射重组过程而失去能量。因此，这种机制的进化以及评估将导致发射效率的提高。在这项研究项目中，我们通过基于三阶的不典型性非上限性，通过暂时的暂时性弹性光谱来观察与载体扩散相关的无辐射过程，非辐射重组引起的热量产生和扩散。到目前为止，尽管它具有重要性，但这种观察很难通过将瞬态透镜光谱与光学显微镜相结合，从而开发了微观的热检测光谱，通过该光学显微镜检查，该光学和临时测量的光热过程与范围内的量化量相结合，可以与量不高的量相结合，并从量不足的量中评估了量不足的量，并可以从降低量的范围中进行扩散。空间分辨率为3μm。结果，已经证实，螺纹脱位在拍照后起激素的非辐射性重组中心起作用。Furthermore。我们已经通过使用一种能够在未来的散发性和非赋形性的过程中进行扫描，该设备可以通过散发出来的发展来进行扫描，因为该设备可以通过散发出来。我们因为不断的研究而进行了进化。达到纳米镜水平。