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Photo-induced Defect Formation and Structural change of Amorphous Silicon Dioxide

非晶二氧化硅的光致缺陷形成和结构变化

基本信息

批准号：
08640431
负责人：
ITOH Noriaki
金额：
$ 0.45万
依托单位：
Osaka Institute of Technology
依托单位国家：
日本
项目类别：
Grant-in-Aid for Scientific Research (C)
财政年份：
1996
资助国家：
日本
起止时间：
1996 至 1998
项目状态：
已结题

项目摘要

The purpose of this investigation is to clarify the models of (1) luminescence, (2) defect formation and (3) structural change, of amorphous materials induced by electronic excitation. Computer simulation and re-examination of existing literatures have been carried out. It is concluded that all phenomena stated above are due to the relaxation of excitons : (1) the luminescence arises from the radiative recombination of self-trapped excitons, (2) defects are metastable states of excitons created at highly distorted amorphous sites and (3) the structural change is induced as a result of radiative and non-radiative recombinations of excitons. Amorphisation of silicon dioxide by dense electronic excitation along heavy ion paths is also investigated. Further details of the study follow. A.The mechanism of defect formation in amorphous materials by electronic excitationThe structure of self-trapped exitons in crystalline silicon dioxide is reinvestigated. It is concluded that self-trapped excitons formed at highly distorted part of amorphous silicon dioxides are converted to metastable states with lower potential barriers than those in crystalline silicon dioxides. B.The mechanism of structural change of amorphous materials by electronic excitationIt is pointed out that the optical absorption change accompanied with structural changes is much larger than that of defect formation and suggested that the structural change is due to alternation of the ground state potential energy surface by formation of excitons.C.The mechanism of amorphisation by dense electronic excitationThe materials in which irradiation with energetic heavy ions register tracks and those in which excitons are self-trapped have been compared. lt is pointed out that the cause of track registrarion is the dense generation of self-trapped excitons. Results have been published in a few reviews on the effects of electronic excitation and in an original paper.

本研究的目的是阐明电子激发引起的非晶材料的（1）发光，（2）缺陷形成和（3）结构变化的模型。对已有文献进行了计算机模拟和重新检验。结果表明，上述现象都是由于激子的弛豫引起的：（1）发光是由自陷激子的辐射复合引起的;（2）缺陷是激子在高度畸变的非晶位上产生的亚稳态;（3）结构变化是激子的辐射和非辐射复合引起的。二氧化硅的非晶化的致密电子激发沿着重离子路径也进行了研究。研究的进一步细节如下。A.电子激发在非晶材料中形成缺陷的机理重新研究了晶体二氧化硅中自陷激子的结构。得出的结论是，自陷激子形成在高度扭曲的部分的非晶硅二氧化物转化为亚稳态具有较低的势垒比那些在晶体二氧化硅。B.电子激发引起非晶材料结构变化的机理.指出伴随结构变化的光吸收变化远大于缺陷形成的光吸收变化，并提出结构变化是由于激子的形成改变了基态势能面.C.电子密集激发引起非晶化的机理.高能重离子辐照引起非晶化的材料比较了寄存器轨迹和激子自陷的轨迹。指出径迹对准的原因是自陷激子的密集产生。结果已发表在一些评论的电子激发的影响，并在一份原始文件。