Ge-Sb-Te相变薄膜的织构形成机制和演化规律研究

Ge-Sb-Te thin films are the key phase change materials of phase change memory. They are characterized by fast phase transformation between amorphous state (disorder) and crystalline state (order). Therefore, the mechanism of reversible phase transformation between amorphous structure and crystalline state is of great importance to phase change memory. There are many factors that affect the phase transformation, one of the factors is texture of thin films. It is inevitable that the texture of thin films will appear during nucleation and growth. But the effect of texture on the phase transformation of Ge-Sb-Te thin films has received less attention. It is of great significance to investigate the texture formation and evolution in the deposition and electrical pulse as well as the effect of microstructure and texture on the electrical/optical properties of Ge-Sb-Te thin films. By designing, adjusting and controlling the texture of Ge-Sb-Te thin films, their properties is optimized, and the performance of the phase change memory is improved. We plan to prepare Ge-Sb-Te thin films by magnetron sputtering method, investigate the texture formation and evolution of Ge-Sb-Te thin films in the deposition and electrical pulse, and the effect of microstructure and texture on the electrical/optical properties of Ge-Sb-Te thin films, in order to further understand the role of texture in the phase transformation. The results of the present work are beneficial to the research and development of phase change materials and phase change memory.

Ge-Sb-Te薄膜是相变存储器的关键材料，其主要特征是可以在无序的非晶态与有序的晶态之间快速转换。因此，Ge-Sb-Te薄膜的非晶态与晶态之间的可逆相变机理是相变存储器研究中的关键科学问题。相变的影响因素有很多，薄膜织构是其中之一，薄膜在形核和长大过程中不可避免地会出现织构，但是薄膜织构对相变的影响问题较少受到关注。研究Ge-Sb-Te薄膜在沉积和电脉冲过程中的织构形成机制和演化规律，建立薄膜微观结构和织构与电/光学性能的关系模型，通过设计、调整和控制Ge-Sb-Te薄膜的织构改善薄膜的电/光性能，对于提高相变存储器的性能意义重大。本项目计划对用磁控溅射法制备的Ge-Sb-Te薄膜，在沉积和电脉冲过程中织构的形成机制和演化规律，以及微观结构和织构类型与强弱对薄膜电/光学性能的影响进行研究，深入认识和理解织构在相变中的作用。

相变存储器具有非易失性、高速存储、低功耗、长寿命和高存储密度等优点，广泛应用于物联网处理器、智能机器人计算系统和汽车电子控制系统等领域。基于相变薄膜在高电阻的非晶态与低电阻的晶态之间的相变，实现数据的写入与擦除。相变薄膜的微观结构、晶体学织构和相变机理对其光-电性能和热稳定性有显著的影响。因此，研究不同体系相变薄膜的微观结构、晶体学织构和相变机理有重要的理论和实际意义。本项目用球差矫正透射电子显微镜、场发射扫描电子显微镜、X射线衍射和电子背散射衍射系统地研究了不同体系相变薄膜的微观结构特征、晶体学织构形成与演化和相变机理，用第一性原理-分子动力学方法建立了液态与非晶态结构模型，研究了薄膜的微观结构特征和相变机理，用综合物性测量系统研究了薄膜的光-电性能和热稳定性。实验和理论研究结果表明，调整薄膜成分、加入不同类型掺杂与缓冲层、调整界面结构对薄膜的微观结构特征、晶体学织构类型、相变机制有重要影响，进而改善光-电性能和热稳定性。本项目研究结果在一定程度上揭示了相变薄膜的微观结构特征、晶体学织构形成与演化规律和相变机理，以及薄膜成分、掺杂与缓冲层类型和界面结构的影响，为控制相变薄膜的微观结构和晶体学织构，改善相变薄膜的光-电性能和热稳定性提供了理论依据。