用正电子湮灭研究电子俄歇复合机制

At high driven currents, the internal quantum efficiency of LED will decrease nonlinearly and even some parts of spectra will lose the ability..These factors will restrict the application of high-brightness LED. Therefore, the investigation on the microscopic physical mechanism of LHD emitting efficiency will have important theoretical significance and practical values. It was found that the Auger recombination process indeed caused the non-linear decline of the efficiency in the InGaN light-emitting materials. However, no any reasonable theoretical demonstration has been given yet. It is one of the important research subjects to establish the physical models and study the realtionship between the emitting efficiency and the transport mechanism f carrier based on the atomic and molecular theory, in order to increase the irradiated recombination process and increase the quantum luminescence efficiently. Due to the advantage of the positron annihiliation process that there is no background signal for Auger recombination process in the spectra of annihilation process, we use the positron annihiliation process to study the Auger recombination process in molecules. The project intends to combine solid band theory and many-body perturbation representation of micro-resonant Auger recombination process to study the nonlinear effects of the luminescence efficiency. And giving the relationship of both the interband and intraband Auger recombination processes with the luminous efficiency. To establish the scheme of increasing the efficiency with the relationship of the distance between atoms in materials, doping type and doping atomic ratio etc. Thereby, improving the luminous efficiency, reducing the heat to provide efficient control mechanism based on the microscopic physical models are the mean goals in this project.

从原子分子的层次上建立降低或消除非辐射复合过程的微观物理模型，探索辐射复合效率与载流子输运机制之间的关系以提高纳米发光材料的量子发光效率，是目前LED发光基础研究领域的热点。利用正电子湮灭过程俄歇谱没有背景散射的优点，本项目拟从原子分子水平上研究纳米和分子发光材料的发光效率与载流子输运及复合机制之间的关系，找到微观量子输运通道与俄歇复合过程之间的关系。从原子分子的激发及其自电离的角度研究和分析各种俄歇复合过程产生的物理机制，包括原子间共振，固体能带间和能带内共振引发的俄歇电子发射现象；运用费曼图分析在复杂环境下各种俄歇复合过程的分枝比，探求主要的俄歇复合机制，进而从原子分子层次上揭示这些主要的俄歇复合过程导致发光效率下降的原因。本项目研究目标是建立共振俄歇复合过程与材料中原子间距离、掺杂原子种类及掺杂比例之间的关系，为遏制俄歇复合过程发生提供调控模型和有效的解决方案。

对于高亮度LED来说，电子等载流子的俄歇复合等非辐射过程引起的发热和频谱漂移甚至损失等非线性问题是制约LED大规模应用的关键问题。从原子分子微观层次上研究清楚这些量子非线性效应对发光效率的影响必将具有重要的理论意义和实际应用价值，也是当前国际科技前沿迫切需要解决的基础问题之一。.项目利用正电子在分子中的湮灭过程，探索研究了俄歇复合等电子关联效应。经过三年的研究，本项目取得了一些重要成果，发现了正电子在分子湮灭过程中出现的新的电子关联现象。（1）提出Docking模型和Positrophilic机制，来研究分子不同位置对电子的作用机制，研究成果分别发表在Journal of the physical society of japan，(2014)83:054301和Physics Letters A(2014)378:1126上。（2）推导出了正电子湮灭伽马谱理论公式，建立了一套求解正电子自洽轨道方法，建立了各种主要俄歇复合过程的物理模型并转化成费曼图式，研究成果发表在Journal of Atomic and Molecular Science, 2015, 6(2), 137-144和Communications in Theoretical Physics, 2016, 65, 531-537，Physics Letters A, 2015, 379, 2306-2310上。（3）提出用正电子湮灭研究发光过程中的俄歇复合过程，这是在本项目的资助下的创造性工作，初步的理论框架和程序已经基本编写完成，也得到了比较有意义的成果，分别发表在Physics Letters A, 2016, 380, 1848-1855和Physical Review A, 2016, 94, 052709-25。.项目利用正电子湮灭过程俄歇谱没有背景散射的优点，研究了大量分子和发光材料中的电子关联效应，为精确研究正电子湮灭伽马谱中的俄歇复合过程，建立更接近实验实际的理论模型打下了基础。初步成果已经以7 篇学术论文的形式在国际刊物上发表，圆满完成项目的任务。