薄膜衬底材料中俄歇电子能谱的蒙特卡洛模拟

发布时间：2018-06-29 01:53

本文选题：俄歇电子能谱 + 蒙特卡洛模拟　；参考：《中国科学技术大学》2017年硕士论文

【摘要】：薄膜材料在现代材料技术中应用广泛。光学镀膜技术中,经常在特定的衬底上沉积一层薄膜,可以改善材料的物理化学性质。许多工业和技术设备都需要覆盖具有特定化学性质的薄膜,薄膜材料具有许多独特的光学与电学性质,这些性质和薄膜本身的制作工艺有关,同时也与薄膜的厚度密切有关。因此,表征纳米量级的薄膜厚度具有十分重要的研究意义。在众多表面分析技术中,俄歇电子的采样深度一般为纳米级别,具有很高的表面灵敏度,适合材料表面定的性和定量分析,因此本文的主要研究目的是:整合当前最新的电子与固体原子的散射理论,用蒙特卡洛方法模拟研究薄膜对衬底俄歇能谱的影响,并用衬底的俄歇峰强度来表征衬底材料上均匀薄膜的厚度,得出俄歇信号强度与薄膜厚度的一般关系式,并推导出相关的有效衰减长度。下面介绍文章的具体内容。在第一章中,我们介绍了俄歇电子以及俄歇能谱应用的基本原理,俄歇电子能谱技术已经成功应用到许多科学领域。然后介绍了薄膜衬底材料的电子能谱学实验中几个常用的物理量:非弹性散射平均自由程和有效衰减长度等。我们还介绍了电子与固体相互作用的散射理论在定量俄歇分析中应用以及实验中应用俄歇谱测膜厚的方法。在第二章中,我们详细介绍了电子与固体相互作用的弹性和非弹性散射理论,以及内壳层激发和俄歇电子产生的原理。本文使用Mott截面描述电子弹性散射,Penn介电函数描述非弹性散射,Gryzinski理论描述内壳层激发和电子弛豫过程。在第三章中,我们首先介绍了蒙特卡洛模拟方法在科学计算领域中的重要应用,以及蒙特卡洛方法在处理电子输运等复杂计和算量巨大的问题的优势所在。然后基于第二章中的散射理论,我们介绍了蒙特卡洛方法在模拟电子在固体中输运的具体过程和详细步骤,并给出了模拟程序的流程图。第四章中,我们以Al薄膜Ag衬底(Al/Ag)和Ag薄膜Cu衬底(Ag/Cu)两种薄膜衬底体系为例,利用蒙特卡洛方法模拟了电子在薄膜衬底材料中的产生和输运,计算了衬底中俄歇电子信号强度随着不同薄膜厚度的变化。模拟得到的电子能谱的能量范围是从入射电子弹性峰到俄歇峰附近,能谱中包括了由电子激发引起的体等离子体损失峰。在弹性峰和俄歇峰的低能区域,出现了来自薄膜和衬底元素的等离子体损失峰。对模拟得到的俄歇电子能谱进行背底扣除后,得到了俄歇峰强度与薄膜厚度的近似指数衰减关系。我们通过表征衰减曲线和有效衰减长度来讨论薄膜厚度的测量。最后定义了一个具有两个参数的衰减函数,发现与程序模拟得到的数据点符合的很好,两参数的衰减曲线可以作为膜厚测量标定曲线。第五章中,对本文进行了总结,并对本文工作的合理扩展以及前景进行了展望。
[Abstract]:Thin film materials are widely used in modern material technology. In optical coating technology, a thin film is often deposited on a specific substrate, which can improve the physical and chemical properties of materials. Many industrial and technical equipments need to cover the thin films with specific chemical properties. The thin film materials have many unique optical and electrical properties which are related to the fabrication process of the film itself and also to the thickness of the film. Therefore, it is of great significance to characterize the thickness of nanocrystalline films. Among many surface analysis techniques, the sampling depth of Auger electron is generally nanoscale, which has high surface sensitivity and is suitable for surface determination and quantitative analysis of materials. Therefore, the main purpose of this paper is to study the influence of thin films on the Auger spectra of substrates by Monte Carlo method, which is based on the latest theory of electron and solid atom scattering. The Auger peak intensity of the substrate is used to characterize the thickness of the uniform film on the substrate. The general relation between the Auger signal intensity and the thickness of the film is obtained, and the effective attenuation length is deduced. The following introduces the specific content of the article. In the first chapter, we introduce the basic principles of Auger electron and the application of Auger spectroscopy, which has been successfully applied to many scientific fields. Then several commonly used physical quantities in the electron energy spectroscopy experiments of thin film substrates, such as the average free path of inelastic scattering and the effective attenuation length, are introduced. We also introduce the application of the scattering theory of electron to solid interaction in quantitative Auger analysis and the method of measuring film thickness by Auger spectrum in experiments. In the second chapter, we introduce the elastic and inelastic scattering theory of the interaction between electrons and solids in detail, as well as the principles of excitation and Auger electron generation in the inner shell. In this paper, we use the Mott section to describe the electron elastic scattering Penn dielectric function to describe the inelastic scattering Gryzinski theory to describe the inner shell excitation and electron relaxation process. In the third chapter, we first introduce the important application of Monte Carlo simulation method in the field of scientific calculation, and the advantages of Monte Carlo method in dealing with the complex problems such as electronic transport and huge computational complexity. Then, based on the scattering theory in Chapter 2, we introduce the concrete process and detailed steps of Monte Carlo method in simulating electron transport in solids, and give the flow chart of the simulation program. In chapter 4, we simulate the generation and transport of electrons in Al thin film Ag substrate (Al/Ag) and Ag thin film Cu substrate (Ag / Cu) by Monte Carlo method. The variation of Auger electron signal intensity with different film thickness was calculated. The energy range of the simulated electron energy spectrum is from the elastic peak of the incident electron to near the Auger peak, and the energy spectrum includes the loss peak of the bulk plasma caused by the electron excitation. In the low energy region of elastic peak and Auger peak, the plasma loss peaks from thin films and substrate elements appear. The approximate exponential attenuation relationship between the Auger peak intensity and the thickness of the film is obtained by deducting the simulated Auger electron spectroscopy. We discuss the measurement of film thickness by characterizing the attenuation curve and effective attenuation length. Finally, a attenuation function with two parameters is defined. It is found that the attenuation curve of the two parameters is in good agreement with the data points obtained by the program simulation, and the attenuation curve of the two parameters can be used as the calibration curve of film thickness measurement. In the fifth chapter, this paper is summarized, and the reasonable expansion and prospect of this paper are prospected.
【学位授予单位】：中国科学技术大学
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：TB383.2

【相似文献】