Rutherford backscattering analysis of thin films and superlattices with roughness
Rutherford backscattering analysis of thin films and superlattices with roughness
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具有粗糙度的薄膜和超晶格的卢瑟福背向散射分析
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发表时间：
2001
期刊：
影响因子：
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通讯作者：
N. Barradas
中科院分区：
文献类型：
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作者：
N. Barradas
在许多系统中，关于薄膜和多层膜的厚度、成分和界面的知识是理解和优化其性能的基础。经常应用于此类研究的技术之一是卢瑟福背向散射(RBS)。然而，在获得的数据中很难考虑界面粗糙度的影响，另一种选择是为粗糙度起决定性作用的特定问题开发专门的数据分析代码。在这项工作中，通过计算粗糙度对视能量分辨率的影响作为深度的函数，在数据分析中考虑了粗糙度的影响。这取决于粗糙度的确切类型，已经实现了三种不同的模型：不均匀层厚度、波纹样品和粗糙的衬底表面。用该方法还可以分析多层膜中的界面混合。可以通过这种方式自动对数据进行拟合，其中粗糙度参数是在拟合过程中推导出来的，为RBS分析提供了一种新的工具。为了检验该程序的有效性和适用性，将该程序应用于多个系统。选择了难以用RBS分析的系统：Si/VS/Si0.65Ge0.35 300 nm/Si0.2Ge0.8 4 nm/Si0.65 Ge0.35 15 nm/Si3 nm，其中VS代表线性成分梯度的虚拟衬底，以及MgO/(Fe25A/Co20A)10多层膜。
Knowledge on the thickness, composition, and interfaces of thin films and multilayers is, in many systems, fundamental for the understanding and optimization of their properties. One of the techniques often applied to such studies is Rutherford backscattering (RBS). However, it has been very difficult to account for the effects of interface roughness in the data obtained, and the alternative has been to develop dedicated data analysis codes for particular problems where roughness plays a determinant role. In this work, the effect of roughness is taken into account in the data analysis by calculating the effect of roughness on the apparent energy resolution as a function of depth. This depends on the exact type of roughness, and three different models have been implemented: inhomogeneous layer thickness, corrugated sample, and rough substrate surface. Interfacial mixing in multilayers can also be analysed with the method developed. Automatic fits to the data can be performed in this way, where the roughness parameters are derived during the fit, providing a new tool for RBS analysis. The code is applied to several systems in order to test its validity and applicability. Systems which are hard to analyse by RBS have been chosen: Si/VS/ Si0.65 Ge0.35 300 nm/ Si0.2 Ge0.8 4 nm/ Si0.65 Ge0.35 15 nm/Si 3 nm thin films, where VS stands for a linearly composition-graded virtual substrate; and MgO /( Fe 25 A/ Co 20 A)10 multilayers.