Department of Electronic Engineering, East China Normal University, Shanghai 200241, China.
State Key Laboratory of Functional Materials for Informatics, Shanghai Institute of Microsystem and Information Technology, Chinese Academy of Sciences, Shanghai 200050, China.
Sci Rep. 2016 Sep 19;6:33639. doi: 10.1038/srep33639.
The optical properties and structural variations of silicon (Si) doped Sb2Te (SST) films as functions of temperature (210-620 K) and Si concentration (0-33%) have been investigated by the means of temperature dependent Raman scattering and spectroscopic ellipsometry experiments. Based upon the changes in Raman phonon modes and dielectric functions, it can be concluded that the temperature ranges for intermediates and transition states are estimated to 150, 120, 90, and 0 K, corresponding to ST, SST25%, SST28%, and SST33% films, respectively. The phenomenon also can be summarized by the thermal evolutions of interband electronic transition energies (En) and partial spectral weight integral (I). The disappearance of intermediate (INT) state for SST33% film between amorphous (AM) and hexagonal (HEX) phases can be attributed to the acceleratory crystallization of HEX phase by Si introduction. It illustrates that the risk of phase separation (Sb and Te) during the cyclic phase-change processes decreases with the increasing Si concentration. The enhanced crystallization behaviors can optimize the data retention ability and the long term stability of ST by Si doping, which are important indicators for phase change materials. The performance improvement has been analyzed qualitatively from the optical perspective.
我们通过温度相关的拉曼散射和光谱椭圆偏振实验研究了硅（Si）掺杂碲化锑（SST）薄膜的光学性质和结构变化随温度（210-620 K）和 Si 浓度（0-33%）的变化。基于拉曼声子模式和介电函数的变化，可以得出结论，中间体和过渡态的温度范围分别估计为 150、120、90 和 0 K，对应于 ST、SST25%、SST28%和 SST33%薄膜。这一现象也可以通过能带间电子跃迁能量（En）和部分光谱权重积分（I）的热演化来总结。SST33%薄膜在非晶（AM）和六方（HEX）相之间中间（INT）态的消失可以归因于 Si 的引入加速了 HEX 相的结晶。这表明在循环相变过程中 Sb 和 Te 相分离的风险随着 Si 浓度的增加而降低。Si 掺杂可以优化 ST 的结晶行为，从而提高数据保持能力和长期稳定性，这是相变材料的重要指标。从光学角度分析了性能的改善。
