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题名	基于相变存储材料的光学功能研究
作者	林金成
学位类别	硕士
答辩日期	2013
授予单位	中国科学院上海光学精密机械研究所
导师	王阳
关键词	相变存储材料, 超分辨光存储，偏振读出, 多阶光存储, 激光诱导二向色性
其他题名	The optical functions based on phase change memory materials
中文摘要	相变存储材料由于其相变速度快、非晶态和晶态之间光学性质差异大、可逆循环性与热稳定性好等优点，使其不仅成功应用于可擦重写光存储中，在光通信和集成光学上也具有潜在应用价值。但目前对于相变存储材料的光学功能应用主要基于其光学常数的调制，对相变存储材料的其他特性及其应用，仍有待进一步探索。本论文的目的在于研究相变材料的一些新的光学特性（如近场调制特性，偏振特性，激光诱导各向异性和荧光特性等），并基于此发展新的光学功能（如超分辨光存储、多阶光存储等），以期应用到光存储中提高器件的容量或密度，此外这些特性对于开发相变材料新的应用（如逻辑器件等）也具有积极意义。研究内容和结果简述如下： 采用二维FDTD和近场-远场转换方法分析了Ag纳米颗粒掺杂Ge2Sb2Te5记录点的近场和远场光分布特性，并与传统的AgOx 散射型Super-RENS作了比较。研究结果表明该结构具有与金属氧化物型Super-RENS相当的超分辨能力，并可以有效简化膜层结构，且有望获得更高的读出稳定性，可应用于超分辨纳米光存储。 利用椭圆偏振光谱数据分析了经不同功率激光初始化后的Si15Sb85薄膜和经不同温度退火处理后的Ge2Sb2Te5薄膜的反射偏振特性。在理论分析部分，区别于文献中的方法，采用p分量和s分量合成反射的椭圆偏振光，从而把其适用范围推广到偏振转动角和椭圆率较大的相变存储材料。提出了利用相变材料实现多阶存储的偏振读出方案，实验证实了其可行性。研究结果对于利用晶化度调制相变材料的反射偏振特性实现多阶光存储具有重要的参考价值。 研究了皮秒脉冲激光（波长532nm，脉宽30ps，重复频率10Hz）作用下Ge2Sb2Te5薄膜的激光诱导二向色性，发现其二向色性的取向与皮秒激光的偏振方向有关，分析表明其偏振敏感二向色性可能来源于各向异性晶化和激光诱导薄膜熔化-凝固后形成的表面微结构的取向排布。研究结果有助于加深理解相变材料的激光诱导晶化机制，其激光偏振调制的二向色性有望应用于多阶光存储中。 研究了Ni2+掺杂Ge2Sb2Te5薄膜的荧光特性，研究表明，随着退火温度或激光初始化功率的提高（即晶化度的提高），晶体场增强，荧光发光强度不断提高。不同晶化度下Ni2+掺杂Ge2Sb2Te5表现出的可调控的荧光特性，不仅从侧面佐证了材料的原子配位结构，而且可以提供一种实现多阶存储的新方式。
英文摘要	The phase change memory materials not only have been successfully used in the erasable optical memory, but also exhibited the potentials in the optical communication and integrated optics applications, due to their advantages including fast phase transition, large optical contrast between amorphous and crystalline states, reversible recycling, high thermal stability and so on. The optical functions of phase change memory materials are mainly realized based on its optical constant modulation, while some other characteristics and their applications of phase change memory materials still need to be further explored. In this dissertation, some new optical characteristics, such as near field modulation, polarization properties, laser induced dichroism and fluorescence properties, of the phase change memory materials were studied. Some new optical functions, such as super resolution optical recording and mutilevel optical recording, were developed based on it to increase the capacity or density of the optical storage devices. Moreover these characteristics will be helpful to develop other new applications of the phase change materials, such as logic devices and so on. Brief contents and results are as follows: The near-field distribution and far-field characteristic of Ag-nanoparticles embedded Ge2Sb2Te5 phase change recording pits were numerically analyzed by the two-dimensional finite-difference time-domain (FDTD) method and the near-field to far-field transition technique. The results were compared with that of the traditional AgOx-type super-resolution near-field structure (super-RENS). The Ag-nanoparticles embedded Ge2Sb2Te5 phase change recording pits were found to have similar super-resolution ability of metal oxide type super-RENS, but with simpler film structure and better readout stability. It can be applied in the super-resolution nano optical recording field. The reflected polarization characteristics of crystallization degree modulated Si15Sb85 and Ge2Sb2Te5 films were theoretically analyzed with the ellipsometer data. The reflected elliptically polarized light was synthesized by the p and s components, which was different from the method used in the reference, so the application scope of this theory can be extended to the phase change memory materials with lager polarization rotation angle and ellipticity. A polarization readout scheme of multilevel phase change recording was proposed based on it. And its feasibility was confirmed experimentally. These results will be helpful to the realization of multilevel optical recording based on the reflected polarization characteristics of phase change materials with different crystallization degrees. The dichroism of Ge2Sb2Te5 films induced by the picosecond laser pulses (wavelength:532nm, pulse width: 30ps, repetition frequency: 10Hz) was studied. The orientation of dichroism was dependent on the polarization direction of the picosecond laser beam. The polarization dependent dichroism may be caused by the anisotropic crystallization and the orientation arrangement of the surface micro-structure formed after laser-induced melting and solidification. These results will be helpful for better understanding of the laser induced crystallization mechanism of phase change materials. The polarization-modulated dichroism can be applied in the multilevel optical recording. The fluorescence characteristics of Ni2+ doped Ge2Sb2Te5 films with different crystallization degrees were studied. The results show that the fluorescence intensity increased with the initialization power or annealing temperature (eg. the crystallization degree). The adjustable fluorescence of Ni2+ doped Ge2Sb2Te5 films can provide some indirect evidences of the material''s atomic coordination structure, and can also supply a new manner to realize multilevel optical recording.
语种	中文
内容类型	学位论文
源URL	[http://ir.siom.ac.cn/handle/181231/16777]
专题	上海光学精密机械研究所_学位论文
推荐引用方式 GB/T 7714	林金成. 基于相变存储材料的光学功能研究[D]. 中国科学院上海光学精密机械研究所. 2013.

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