Cu－37at％ Ag共晶合金的离子溅射研究

侧重研究了入射Ａｒ＋离子不同剂量轰击时表面微形貌和溅射原子角分布之间的关联，并建议用“元素按靶点表面微形貌特征局域富集模型”来解释溅射原子角分布形状以及择优溅射曲线的变化；发现其结果与实验相符合。     

薄层活化法Fe、Ti基材料表面损失过程方法研究

带电粒子薄层活化法(TLA)以其高灵敏、非破坏和有利情况下在线监测的特性,在磨损、腐蚀、溅射等材料表面损失过程监测和研究中具有独特的优势。Fe和Ti是两种最常见的军用和军民两用材料。本工作以选择能量的p和d活化反应,分别研究了0～80 μmFe和0～150 μmTi表面层范围内生成核放射性强度与表面层深度的函数关系。     

模拟高放玻璃固化体P19-5的浸出行为

用静态浸出试验研究了模拟高放玻璃固化体P19-5在不同温度下的浸出行为,选用Ce作为Pu的模拟元素。通过测试分析各元素的归一化质量损失和玻璃表面层形貌、成分随浸泡时间的变化,讨论了玻璃固化体的浸出机制和Ce在玻璃表面层中的保留机制。研究发现：在25, 40, 70 ℃条件下玻璃固化体的浸出率相差不大,比90 ℃下的浸出率约小1个数量级;Gd和Ce的浸出率比其它主要成分(Si, B, Li等)低2～3个数量级;浸泡过程中,Gd和Ce绝大部分都继续保留在表面层中,其主要保留机制为原位重构。     

离子溅射诱发单相合金Cu—12at.%Au表面“元素局域富集”

用扫描电子显微镜结合电子探针微分析技术测定了溅谢诱发的靶点表面成份变化，观察了表面形貌结构凸起和凹陷处的成分差别，实验结果表明，单相合金Ｃｕ－１２ａｔ．％Ａｕ在３０ｋｅＶ Ａｒ＾＋离子溅射过程中产生了“表面元素局域富集”现象。根据“溅射－形貌增强元素局域富集模型”，它包括元素局域富集初级阶段和毛细压力发生的选择性诱发力的作用，并据此对实验结果进行了讨论。     

20—80keV Ar~+离子对稀释Si(Co,Ta)合金的溅射

荷能离子对单元素的溅射已有较好的理论解释,但是对多元合金或化合物溅射的研究才开始不久,目前尚无一个能够成功地解释实验现象的理论。 溅射后合金样品近表面组成的改变,是一种有趣的实验现象。实验中发现三元合金的现象比二元合金更为复杂,例如,元素的近表面改变与溅射离子的能量有关,这是用现有的择优溅射理论无法解释的。为研究这种现象,我们选取了Si(Co,Ta)三元合金,在分别用20到     

Al_xSn_（100－x）合金系统的Ar~＋溅射研究

用捕获膜和卢瑟福背散射技术给出了３０ｋｅＶＡｒ＋轰击ＡｌｘＳｎ１００－ｘ合金系统（Ｘ＝９０，７０，５０，３０，１０）溅射Ｓｎ和Ａｌ原子的角分布及其择优溅射变化。提出一个考虑靶点表面形貌和元素局域富集对发射原子影响的模型，分析结果和实验数据符合较好．     

90－19／U模拟高放废物玻璃固化体表面性能的研究

本文对９０－１９／Ｕ模拟高放废物玻璃固化体的表面性能进行了研究。实验结果表明，固化体与水反应会导致固化体表面层的产生，表面层中Ｌｉ、Ｎａ、Ｂ等易溶元素发生贫化，而Ｕ、Ｆｅ、Ｔｉ、Ｍｇ、Ｃａ等元素发生不同程度的富集；随反应程度不同，表面层厚度也不同，且在反应进行至一定程度后，表面层会发生不同程度裂缝和脱落，并产生表面沉积物。     

90—19／U模拟高放废物玻璃固化体表面性能的研究

本文对９０－１９－Ｕ模拟高放废物玻璃固化体的表面性能进行了研究。实验结果表明，固化体与水反应会导致固化体表面层的产生，表面层中Ｌｉ、Ｎａ、Ｂ等易溶元素发生贫化，而Ｕ、Ｆｅ、Ｔｉ、Ｍｇ、Ｃａ等元素发生不同程序的富集；随反应程度不同，表面层厚度也不同，且在反应进行至一定程度后，表面层会发生不同程度裂缝和脱落，并产生表面沉积物。     

元素溅射率与离子束入射角的关系

Yamamura指出:若能量为E的离子束倾斜轰击多晶元素靶,则原子相对溅射率y(θ)=Y(θ)/Y(0°)随离子束入射角θ变化的曲线可表示为含二个参数的经验公式:y(θ)=t~f·exp{g-(t-1)},t=secθ。其中,f和g是待定参数,其值由实验决定。g=f·cosθ_0,θ_0是元素溅射率Y(θ_0)达到最大值时的离子束最佳入射角。 我们导出了离子束的最佳入射角拟合公式(8),并讨论了它的物理意义。因而,含二个参数的Yamamura经验公式(1)变成只含一个参数的原子相对溅射率公式(4)。其中,待定参数f的值由解析公式(21)给出。     

高剂量注入中离子溅射的影响

在离子注入材料改性的研究过程中(金属、绝缘材料和光学材料等),在许多场合下,要求注入的元素(如Fe中注入N、Y、Ph和Sn等)在靶子中占百分之几的含量,这就要求注入剂量高达10~(17)/cm~2到10~(12)/cm~2。由于离子注入的溅射效应在低能和大剂量注入中是相当明显的,因此,对这些元素高剂量注入后的杂质分布、溅射系数、溅射厚度和靶子中杂质的收集量做一分析是十分重要的。     

Angular distributions of Ni and Ti atoms sputtered from a NiTi alloy under He and Ar ion bombardment

The angular distributions of sputtered components were measured for NiTi polycrystalline alloy under 9 keV Ar⁺ and He⁺ ions bombardments with various fluences in ultrahigh vacuum. Combination of Rutherford Backscattering Spectrometry (RBS) and Auger Electron Spectrometry (AES) techniques allowed us to observe enhanced concentration of Ni over a layer with thickness comparable to a primary He⁺ ions penetration depth due to selective sputtering of Ti atoms and radiation-induced diffusion processes. A preferential emission of Ni atoms towards the surface normal was observed during bombardment by both He⁺ and Ar⁺ ions. More forward-peaked “over-cosine” angular distributions of sputtered Ni in comparison with those for Ti atoms have been measured. Nonstoichiometric sputtering of NiTi alloy dependent on emission angle was observed for bombardment fluence of He⁺ well below that needed for the steady-state altered layer formation. To explain the peculiarities of NiTi sputtering, an interpretation is discussed in terms of sputtering due to backscattered He⁺ ions.     

Erosion yield of Ti from TiC-deposited graphite by hydrogen ion bombardment at high temperatures

Erosion yields of Ti atoms from a TiC-deposited graphite by bombardment with 1 keV hydrogen ion beam of various current densities at 900°C have been investigated by means of the Rutherford backscattering (RBS) technique. It has been observed that the sputtering yields for Ti atoms at 900°C are almost zero below a critical ion flux of 1 × 10¹⁵/cm²·s, compared with the sputtering yield of Ti atoms at room temperature which has been measured to be 1 × 10⁻²atoms/ion. No sputtering of Ti atoms observed at 900°C is explained in terms of self-sustaining coating of the TiC surface with segregated carbon layer. The condition for the self-sustaining coating is discussed.     

Erosion of tungsten-doped amorphous carbon films in oxygen plasma

Tungsten-doped amorphous carbon films with 0–9 at.% W concentration were produced by magnetron sputtering and eroded in oxygen plasmas applying different bias voltages and substrate temperatures. The partial C and W erosion rates were determined from the C and W areal density changes measured by Rutherford backscattering spectrometry (RBS). The initial C removal rate increases with increasing ion energy and temperature and decreases with increasing W concentration. For W-doped films the erosion rate decreases with increasing plasma exposure duration. At low bias voltages the erosion process stops after W accumulation at the surface, which protects the carbon underneath from further erosion. RBS and X-ray photoelectron spectroscopy suggest that the W-rich layer at the surface is carbon free and consists of porous WO₃. Biasing to 200 V leads to removal of W by physical sputtering and, therefore, inhibits the formation of the protecting W oxide layer and the C erosion proceeds.     

Layer morphology analysis of sputter-eroded silicon gratings using Rutherford backscattering

The possibility to simulate Rutherford backscattering (RBS) spectra from arbitrary laterally inhomogeneous sample structures was implemented in the SIMNRA code. Layer morphology is modeled by a layer thickness frequency distribution. This method was used to monitor the evolution of the surface morphology of a one dimensional silicon grating on top of a tantalum interlayer in situ. The Si grating was sputtered by argon and carbon ion beams at an incident energy of 6 keV at two different angles of incidence parallel to the grid lines. After each sputtering step the surface was investigated by RBS. The Si grid lines undergo a change of their morphology due to sputtering erosion. The morphology change depends on the sputtering angle and is different for Ar and C bombardment. Sputtering with C leads to the formation of a protective C layer on top, which was confirmed by additional NRA measurements. The results of the RBS measurements were confirmed by scanning electron micrographs of sample cross-sections produced by focused ion beam cross-sectioning.     

Argon irradiation damage at a Cu/Al2O3 interface for different alumina structures

The evolution of damages at a Cu/Al₂O₃ device interface after Ar⁺ irradiation, depending on alumina structure, and the effect of surface roughness on sputtering have been studied. A polycrystalline Cu/Al₂O₃ bilayer and polycrystalline Cu on amorphous alumina were irradiated with 400 keV Ar⁺ ion beam at doses ranging from 5 × 10¹⁶ to 10¹⁷ Ar⁺/cm² at room temperature. The copper layer thicknesses were between 100 and 200 nm. RBS analysis was used to characterize the interface modification and to deduce the sputtering yield of copper. The SEM technique was used to control the surface topography. A RBS computer simulation program was used to reproduce experimental spectra and to follow the concentration profile evolutions of different elements before and after ion irradiation. A modified TRIM calculation program which takes into account the sputtering yield evolution as well as the concentration variation versus dose gives a satisfactory reproduction of the experimental argon distribution. The surface roughness effect on sputtering and the alumina structure influence at the interface on mixing mechanisms are discussed.     

High temperature oxidation resistance of fluorine-treated TiAl alloys: Chemical vs. ion beam fluorination techniques

The modification of the alloy surface by halogens significantly improves their oxidation behaviour at high temperature. It corresponds to the preferential reaction of the aluminium with the applied fluorine at the oxide/alloy interface and it promotes the growth of an adherent and stable alumina layer.Well-defined fluorine profiles beneath the surface of the material can be achieved by either fluorine beam line ion implantation (BLI²) or plasma immersion ion implantation (PI³). As an alternative to the implantation-based approach, chemical fluorination techniques such as gas-phase treatment and dipping in F-based solutions were also investigated. The fluorine depth-profiles were measured before and after oxidation at 900 °C using non destructive ion beam analyses: Proton Induced Gamma-ray Emission (PIGE), Rutherford Backscattering Spectroscopy (RBS) as well as Elastic Recoil Detection Analysis (ERDA). It enables to control and to optimise the fluorination conditions of technical TiAl alloys for an industrial application.     

Dynamic Monte Carlo simulation of surface composition change during sputter depth profiling

In the surface analysis methods such as X-ray photoelectron spectroscopy, Auger electron spectroscopy, or secondary-ion mass spectroscopy, sputtering processes are used for depth profiling. However, ion beam bombardment changes the surface composition and the surface structure, which deteriorates the accuracy of the surface analysis and the depth resolution. We studied the preferential sputtering in some materials consisting of two components with different mass ratio by using the dynamic Monte Carlo simulation. Dose dependence of the depth profile of composition is presented. By Ar sputtering, the surface compositions of Au_0.25Cu_0.75, Au_0.67Al_0.33, and Ni_0.5Cu_0.5 alloys changed to Au_0.28Cu_0.72, Au_0.76Al_0.24, and Ni_0.67Cu_0.33, respectively. These results agreed with the experimental data. In order to compare the effect of mass ratio on the preferential sputtering, B–C, Si–C, and W–C systems were investigated. In B–C system, preferential sputtering by 1 and 3 keV Ar ion was negligible. In W–C system, a significant preferential sputtering occurred. In Si–C system, carbon was enriched in the outermost surface layer at a fluence lower than 3×10¹⁶ ions/cm². At higher fluence, the partiality in concentration recovers because of the balance between the enrichment and the preferential sputtering.