Photo-Induced Structural Change in Hydrogenated Amorphous Silicon

氢化非晶硅的光致结构变化

• 批准号: 09650357
• 负责人: OKAMOTO Hiroaki
• 金额: $ 2.3万
• 依托单位: Osaka University
• 依托单位国家: 日本
• 项目类别: Grant-in-Aid for Scientific Research (C)
• 财政年份: 1997
• 资助国家: 日本
• 起止时间: 1997 至 1998
• 项目状态: 已结题
• 来源: https://kaken.nii.ac.jp/grant/KAKENHI-PROJECT-09650357/
• 关键词: Amorphous Semiconductor; Photo-Induced Degradation; Polarized Electroabsorption; Structural Change; Density; Internal Stress; 偏光エレクトロアブソ-プション

Polarized electroabsorption (PEA) method has been used to study photo-induced structural changes in hydrogenated amorphous silicon.The field-modulated absorption consists of two components, one of which is the true polarization-dependent electroabsorption serving as an indicator of the structural disorder, and the other is the thermoabsorption originated in the temperature modulation due to Joule heating.The thermoabsorption component has to be removed from the observed field-modulated absorption signal to make an accurate and reliable evaluation of structural disorder in terms of the polarization dependence of the electroabsorption signals, since an increase in the sample resistance owing to the light-induced degradation should give a large impact on the magnitude of the thermoabsorption signal.The phase-separation procedure has been applied to deconvolute the observed field-modulated absorption signal into two components, leading to a result that about 15-25% of the observed signal a … More rises from the thermoabsorption effect for the Tauc gap region.Nevertheless, any essential alternation is not needed for our previous PEA result that the structural disorder is increased upon light-exposure.The internal stress as well as mass density have been measured to provide alternative evidences for the photo-induced structural change by the use of the bending-beam method and floatation method, respectively.It is found from these results that amorphous silicon films expand and the density tends to decrease upon light-exposure.The dynamics of the change in the PEA disorder, internal stress, mass density and metastable defect density under light exposure have been systematically investigated in order to resolve the essential link among them.The change in internal stress as well as mass density appears to be strongly dependent on the duration of light exposure pulse even through the accumulated exposure time is fixed, whereas such a peculiar behavior does not occur for the PEA disorder.The experimental findings lead us to an idea that the photo-induced increase in the net-work disorder shall result in an accumulation of the local net-work stress, and then a creation of metastable defects.The causality relation is formulated in the simplistic physical basis, which gives a clear-cut interpretation for the observed dynamics of the photo-induced structural change and creation of metastable defects in a semi-qualitative manner.If our new idea were true, then the removal of the photo-induced degradation should be established by interrupting the link ; increases in the new-work disorder, accumulation of local net-work stress, and creation & stabilization of metastable defects. Less

用偏振电吸收(PEA)方法研究了氢化非晶硅的光诱导结构变化。场调制吸收由两部分组成，一部分是作为结构无序指标的真偏振相关电吸收，另一部分是焦耳加热引起的温度调制产生的热吸收。为了准确、可靠地从观察到的场调制吸收信号中去除热吸收成分，以电吸收信号的极化相关性对结构无序进行准确可靠的评价，由于光致退化引起的样品电阻的增加将对热吸收信号的大小产生很大的影响。应用相分离过程将观测到的场调制吸收信号去卷积成两个分量，结果导致大约15%-25%的观测信号a…然而，我们以前的PEA结果并不需要任何必要的改变，即结构无序随着光照的增加而增加。我们分别用弯曲光束法和浮选法测量了结构无序的内应力和质量密度，为光致结构变化提供了替代的证据。从这些结果中发现，非晶硅薄膜在光曝光后膨胀，密度趋于减小。PEA无序、内应力和质量密度的变化动力学系统地研究了光曝光下的质量密度和亚稳态缺陷密度之间的本质联系。即使在累积曝光时间固定的情况下，内部应力和质量密度的变化也强烈地依赖于光曝光脉冲的持续时间，而对于PEA无序来说，这种特殊的行为不会发生。实验结果使我们认为，光诱导的网络无序的增加将导致局部网络应力的积累，从而产生亚稳态缺陷。因果关系建立在简单的物理基础上，它以半定性的方式对观察到的光诱导结构变化和亚稳态缺陷产生的动力学给予了明确的解释。如果我们的新想法是正确的，那么光诱导退化的去除应该通过中断连接来建立；新网络无序的增加，局部网络应力的积累，以及亚稳态缺陷的产生和稳定。较少

项目成果

服部公則: "Photomodulated electron-spin resonance in amorphous Silicon" J.Appl.Phys.84. 4974-4978 (1998)

Kiminori Hattori：“非晶硅中的光调制电子自旋共振”J.Appl.Phys.84 4974-4978 (1998)。

清水耕作: "Photo-induced Structural Changes in Hydrogenated Amorphous Silicon" Material Research Society Symposium Proceedings of Amorphous Silicon Technology-1998. (in press).

Kousaku Shimizu：“氢化非晶硅中的光致结构变化”材料研究学会非晶硅技术研讨会论文集 - 1998（印刷中）。

K.Shimizu, T.Tabuchi, K.Hattori, H.Kida and H.Okamoto: ""Photo-induced Structural Changs in Hydrogenated Amorphous Silicon"" Material Research Society Symposium Proceedings of Amorphous Silicon Technology-1998, California. (in press.). (1998)

K.Shimizu、T.Tabuchi、K.Hattori、H.Kida 和 H.Okamoto：“氢化非晶硅中的光致结构变化””材料研究学会非晶硅技术研讨会论文集 - 1998 年，加利福尼亚州。

H.Okamoto: ""Optical Absorption Spectrum of Amorphous Semiconductors" (in Japanese.)" Solid State Phys.32. 63-68 (1997)

H.Okamoto：““非晶半导体的光学吸收光谱”（日文）”固态物理.32。

清水耕作: "Photo-induced Structural Change and defect creation in Hydrogenated Amorphous Silicon" J.Non-Cryst.Solids. 227-230. 267-271 (1997)

Kousaku Shimizu：“氢化非晶硅中的光致结构变化和缺陷产生”J.Non-Cryst.Solids 227-230 (1997)。