钛锑碲相变材料非线性光学性质机理研究

The mechanism of nonlinear optical properties of TiSbTe phase change materials .As a new kind of phase change materials, TiSbTe (TST) exhibits lots of excellent properties compared with traditional phase change materials, such as good reversible phase change ability, rapid crystallization speed, better data retention and higher crystallization temperature. When TST is applied to recording medium of phase change memory (PCM), information written/erasure can be realized to use electrical or thermal energy to drive TST to transform mutually from crystallization to amorphous state. According this property, TST can be also applied to recording and mask layer of optical recording. In order to achieve this purpose, magnetron sputtering method is used to prepare TST film, Z-scan technology is used to measure nonlinear optical properties of TST film. The main contents of this study are as following: 1. to prepare a series of homogeneous TST films with different thickness and dense surface; 2. to establish improved Z-scan device in order to measure nonlinear absorption coefficient and nonlinear refractive index of TST films; 3. to investigate mechanism of the nonlinear optical properties, to build simulation models based on the mechanism, theoretical nonlinear absorption coefficient and nonlinear refractive index can be derived from the models, compare theoretical with experimental data, the accuracy of the mechanisms can be tested and verified. The key problem of this study is to obtain nonlinear absorption coefficient and nonlinear refractive index of TST films through theoretical derivation and experimental methods.

钛-锑-碲（TiSbTe)是一种新型的相变材料，具有相变速度快，数据保持力好、结晶温度高的特点，作为相变存储器（PCM)的存储介质，利用电能 (热量）使材料在晶态(低阻）与非晶态(高阻）之间相互转化实现信息的写入和擦除。根据此种性质，同样可将其用在光存储的记录层和掩膜层。为了拓展此种材料在光学方面的应用，本研究将以磁控溅射法制备TiSbTe薄膜，以Z扫描法测量其非线性光学性质。本项目的主要研究内容分为三个部分：1制备一系列不同厚度、表面致密、成分均一的TiSbTe薄膜；2搭建改进型Z扫描装置，测量薄膜的非线性吸收系数和非线性折射率；3分析产生非线性光学性质的微观机理，并搭建理论模型，通过仿真计算得出非线性吸收系数和非线性折射率的理论值，与实验得到的数据对比，以验证微观机理的准确性。拟解决的关键问题为通过实验和理论推导两种方法得到TiSbTe的非线性吸收系数和非线性折射率。

本项目系统的研究了超分辨近场结构中用于掩膜层的钛锑碲(TiSbTe)薄膜的光学性质、非线性光学性质，具体研究内容和结论如下：.研究了磁控溅射参数对样品薄膜表面形貌的影响并优化了溅射工艺参数。溅射气压、溅射功率和偏压会影响成膜的致密程度和表面粗糙度。制备高质量的薄膜，是以后一系列实验的基础。.使用椭偏仪和XRD测量了厚度和温度对TiSbTe薄膜光学常数和结构的影响，结果显示：1）薄膜晶化程度随膜厚和温度的增加而提高。2）光学常数随厚度的变化具有临界值，为30 nm，当厚度小于临界值时，光学常数随厚度的变化明显，而大于30 nm，光学常数则基本无变化。3）沉积态和晶态薄膜的光学常数不同，对于具有特定组成的样品薄膜，影响其折射率的主要因素是微观结构。沉积态样品薄膜覆盖ZnS-SiO2做保护层后，做原位变温椭偏测量，发现随着温度的升高，折射率下降而消光系数升高。微观结构和膜层间内应力是影响折射率的主要原因。.利用Z扫描实验测试TiSbTe薄膜的非线性吸收特性，薄膜表现出非线性饱和吸收，晶态样品薄膜消光系数随温度的变化关系：随着温度的上升而减小，主要影响因素来自于晶态样品内的共振吸收。