Quantitative analysis of silicon-oxynitride films by EPMA

Thin films of silicon oxynitride with diverse compositions were prepared by de-magnetron sputtering of silicon, utilising oxygen and nitrogen gas flows and the sputtering power to vary the composition. In order to investigate the composition of these films, a method of analysis by electron probe micro analysis with energy dispersive detection was developed and the figures of merit were compared to the wavelength dispersive method used by other authors. The precision and repeatability of the results are evaluated and the accuracy is checked by comparison with Rutherford backscattering and nuclear reaction analysis. Energy dispersive X-ray spectrometry was proven to be applicable to analyse silicon oxynitride films of any composition yielding quantitative results for nitrogen and oxygen as well as silicon. Besides the good analytical performance, electron probe micro analysis with energy dispersive X-ray spectrometry has turned out to be a non-destructive, quick, easy to use and cost effective tool for the routine analysis of light elements in thin films.     

Investigations in the ternary system Ti-Mo-N by means of EPMA and XRD

Arc-melted ternary Ti-Mo-N alloys were heat treated at 1423 K in order to evaluate the compositions of the equilibrium phases. The composition of the bcc phase-Ti _x Mo_1–x with respect to Mo and Ti was determined by electron probe microanalysis (EPMA) and lattice parameter measurements (XRD). In order to avoid the effects of plastic deformation caused by powdering the ductile-Ti _x Mo_1–x alloys, the lattice parameter measurements were carried out on small particles of the compact samples using Debye-Scherrer cameras. The EPMA and XRD results agree within the expected range of accuracy. Apparently the solubility of nitrogen in-Ti _x Mo_1–x is low and does not perceptibly affect EPMA and XRD results. The relationship between the lattice parameter and the nitrogen content of-TiN_1–x was applied to determine the composition of-TiN_1–x in equilibrium with-Ti_xMo_1-x No solid solubility of Mo in TiN_1–x could be detected. The tie lines at 1423 K between the two phases were established.     

Quantitative electron probe microanalysis of Y-Ba-Cu-O superconducting materials

The high temperature superconductor YBa₂Cu₃O_7–x has been studied by quantitative electron probe microanalysis (EPMA). After investigation of appropriate standards and choice between three different matrix correction methods this technique provides very accurate analytical results including those for oxygen. The quantitative results even allow the determination of the stoichiometry with deviations less than 2% relative. The application of computercontrolled EPMA is demonstrated by the characterization of the microstructure of a ceramic Y-Ba-Cu-O sample. Finally the properties of copperL ₂ andL ₃ valence band spectra are presented for compounds with copper in different valence state.Dedicated to Professor Günther Tölg on the occasion of his 60th birthday     

EPMA analysis of float glass surfaces

This work concentrates on the setting-up of conditions for the quantitative analysis of the composition profiles of major and minor components of float glass surfaces with an electron probe micro-analyser. Since surfaces are modified for depths of 10–50 m, they have been studied both in polished cross-section and perpendicularly to the electron beam by varying its energy to investigate the near-surface region (0–3m). The results demonstrate that combined use of the two methods supplies complete and continuous information on the quantitative distribution from large depths to the first layers of the float surfaces. The experimental conditions, sample preparation, in-depth and lateral resolutions, precision and accuracy of the methods are also investigated.     

Investigation of implanted gallium depth distributions in ZnSxSe-x by EPMA

In the present work EPMA combined with Monte Carlo simulation was applied to investigate implanted gallium depth distributions in ZnS_xSe_1–x layers. The layers of about 1 to 4 m thickness were grown by MOVPE on (100)-GaAs substrate. The overlap of the Ga and zinc L X-ray spectra and the low gallium net count rates were overcome by stripping the spectra of non implanted layers and by applying appropriate beam currents and counting times. Capabilities and limitations of the EPMA technique as applied to depth profile analysis are demonstrated.Despite the mentioned L interference, the detectability limit of EPMA for 340 keV Ga in ZnS_xSe_1–x is as low as 10¹⁴ cm^–2. The measured Ga L intensity versus beam energy curves reveal variations of the Ga depth profiles during annealing. Evaluation of the intensity curves by means of Monte Carlo simulations yields the implanted dose densities and the first two moments of the depth distributions, i.e. the projected range and its standard deviation. The nonannealed profiles agree well with expectations, but after thermal annealing the profiles were significantly shifted towards the surface. Comparison of EPMA and SIMS results with the example of a non annealed profile in ZnSe has shown good agreement.     

Quantitative Analysis of Thin Aluminium-Oxynitride Films by EPMA

 Thin films of aluminium oxynitride with diverse composition were prepared by dc-magnetron sputtering of aluminium, utilising sputtering power as well as argon, oxygen and nitrogen gas flows to vary the composition. Since film properties depend mainly on the content of incorporated oxygen and nitrogen, a method for quantitative analysis of the main constituents based on electron probe micro analysis with energy dispersive detection was developed. The excellent precision of the quantitative results for aluminium as well as oxygen and nitrogen are shown. Furthermore, a film layer analysis program was applied for the quantification of several films deposited under the same deposition parameters on silicon wafers, from 520 nm down to 40 nm thickness, showing that electron probe micro analysis with energy dispersive detection is a reliable method for quantitative compositional analysis of thin aluminium oxynitride films down to approximately 20 nm thickness. Since this method of analysis provides only bulk information, expected inhomogeneities of the depth distribution of the film components were checked by secondary ion mass spectrometry depth profiles of two thin films and correlated to the EPMA results. The thickness of the films was determined by ellipsometry. Received September 1, 1998     

Quantitative analysis of W-C:H coatings by EPMA,RBS (ERD) and SIMS

Several analytical techniques have been used to characterize homogeneous films of tungsten-containing hydrogenated carbon (W-C: H), deposited on Si with a film thickness of 1–1.5 m. Electron probe microanalysis (EPMA) enables one to determine the major components W (3–43 at %) and C, impurities (< 2 at %) of Ar and O, and the mass thickness (300–1800 g/cm²) of the films. The agreement between the results of EPMA and the data (W-content, mass thickness) provided by Rutherford backscattering spectrometry (RBS) is 5–10% relative. Quantitative analysis of hydrogen in W-C:H films (1–16 at %) is carried out by the technique of elastic recoil detection (ERD). A suitable scheme for the determination of H in W-C: H films by SIMS is proposed, based on monitoring the intensity ratio of HCs⁺/CCs⁺ secondary ions.     

Accurate Determination of Trace Amounts of Oxygen in CrAlN Hard Coatings by a Combination of WDS–EPMA and SIMS

Low amounts of oxygen in AlCrN hard coatings have been quantitatively analysed by means of WDS–EPMA. By combination with SIMS depth profiling, applying a calibration sample produced by ion implantation, the accuracy of the EPMA results was proven. Values as low as 0.07 at% were measured and the calculated detection limit is in the range of 0.01 at%.     

高频红外碳硫分析仪测定含碳化硅耐火材料中碳化硅含量

采用对试样进行灼烧预处理的方法,除去游离碳,用锡粒、纯铁、钨粒作为助熔剂,并以钢铁标准样品校正仪器,高频燃烧红外吸收法测定含碳化硅耐火材料中的碳化硅含量,测定结果的相对标准偏差为1.07%(n=6),该法与化学法的测定结果较接近,精密度和准确度均满足化学分析的要求。     

熔盐电解SiO2/C直接制备SiC纳米线

采用纳米SiO₂和酚醛树脂为原料制备酚醛树脂裂解碳纳米SiO₂复合阴极(硅碳物质的量的比为1∶1),直接电解PFC/SiO₂复合阴极,在900 ℃熔融盐CaCl₂中,恒槽压2.0 V下电解,制备出碳化硅纳米线。采用场发射扫描电子显微镜(FESEM)、透射电子显微镜(TEM)、高分辨透射电子显微镜(HRTEM)及其附带的能谱仪、X射线分析衍射仪(XRD)和拉曼光谱(Raman)对产物的组成、形貌、微观结构等进行了表征。结果表明：碳化硅纳米线呈立方晶体结构,其直径为4~13 nm,长可达数微米;室温下该纳米线在415 nm和534 nm附近有宽的发光峰。最后,讨论了碳化硅纳米线的生成机制。     

熔盐电解SiO2/C直接制备SiC纳米线

采用纳米SiO₂和酚醛树脂为原料制备酚醛树脂裂解碳纳米SiO₂复合阴极(硅碳物质的量的比为1:1),直接电解PFC/SiO₂复合阴极,在900℃熔融盐CaCl₂中,恒槽压2.0V下电解,制备出碳化硅纳米线。采用场发射扫描电子显微镜(FESEM)、透射电子显微镜(TEM)、高分辨透射电子显微镜(HRTEM)及其附带的能谱仪、X射线分析衍射仪(XRD)和拉曼光谱(Raman)对产物的组成、形貌、微观结构等进行了表征。结果表明:碳化硅纳米线呈立方晶体结构,其直径为4~13nm,长可达数微米;室温下该纳米线在415nm和534nm附近有宽的发光峰。最后,讨论了碳化硅纳米线的生成机制。     

XRD-Studies of SiC/Si layers on carbon substrates

Structural investigations of thin films of SiC, SiC with free silicon and various titanium suicides (TiSi₂, TiSi and Ti₅Si₃) are described. The crystal phases have been identified using X-ray diffractometry. The growth of reaction products from surface reactions between silicon and deposited titanium can be observed.Dedicated to Professor Dr. rer.nat. Dr. h.c. Hubertus Nickel on the occasion of his 65th birthday     

Determination of thickness distribution and composition of thin coatings by EPMA: Application in the field of steel sheet production

A new method for the investigation of surface coatings by EPMA is presented. It is based on a physical model which takes into account the X-ray intensity depth distribution, the absorption and the electron backscattering effects at the interface between film and substrate. When combined with the concentration mapping (CM) technique, a two-dimensional film thickness distribution and the film composition can be determined simultaneously. Only bulk standards are required for this method.With some examples in the field of steel sheet production and electrogalvanizing the versatility of the method as well as its high sensitivity are pointed out. Particularly important for practical work is the applicability to almost any combinations of film and substrate materials as well as the wide thickness range from almost the total X-ray emergence depth down to the monolayer range.Dedicated to Professor Günther Tölg on the occasion of his 60th birthday     

硅钼蓝光度法测定碳化硅中二氧化硅的含量

采用氯化钠-盐酸-氢氟酸溶解碳化硅样品,加钼酸铵使硅酸离子形成硅钼杂多酸,然后用1-氨基-2-萘酚-4-磺酸还原剂将其还原成硅钼蓝,在700nm波长处测定其吸光度,从而测得碳化硅中的二氧化硅含量。考察了称样量、水浴温度、水浴加热时间、样品储存容器、显色反应时间等因素对测定结果的影响,优化了测试条件。二氧化硅的质量浓度在0．25-12．5mg／（100mL）的范围内与吸光度呈良好的线性关系,线性相关系数r=0．99986。加标回收率为99．2％～100．9％,测定结果的相对标准偏差为0．76％（n=6）。     

Initial formation of contact layers on Ni/SiC samples studied by XPS

This study deals with the quantitative assessment of the coverage and thickness of Ni silicide films formed during annealing of SiC substrates with sputtered thin films of Ni. The analytical approach involves the use of XPS and depth profiling by means of successive ion etchings and XPS analyses. For either 3 or 6 nm initial Ni film thickness, a 10 nm Ni₂Si product is formed. On top of this product, the C released is accumulated in a very thin (1–2 nm) film. In neither case, the Ni₂Si covers the whole surface, although the coverage is almost complete (～90%) in the latter case. For the greater initial Ni‐film thickness of 17 nm, the thickness of the Ni₂Si product corresponds well to the value of 25 nm expected from the Ni/Ni₂Si stoichiometric relationship. This thickness is significantly greater than a critical level and the film covers the whole surface. Carbon is similarly accumulated in a very thin layer on the top surface, although the major part of C (～70%) is found inside the main reaction product layer. Copyright © 2008 John Wiley & Sons, Ltd.     

NanoSIMS and EPMA analysis of nickel localisation in leaves of the hyperaccumulator plant Alyssum lesbiacum

Certain plants known as ‘metal hyperaccumulators’ can accumulate exceptional concentrations of elements such as zinc, manganese, nickel, cobalt, copper, selenium, cadmium or arsenic in their above ground tissue. In members of the genus Alyssum, nickel concentrations can reach values as high as 3% of leaf dry biomass. These plants must possess very effective mechanisms for the transport, chelation and sequestration of such elements within their tissues to avoid the toxic effects of free metal ions. Evidence from a number of different techniques suggests that nickel is concentrated primarily in the outermost, epidermal tissue of leaves of Alyssum hyperaccumulators, but there is currently no consensus on the principal sites of nickel sequestration. In this study, high resolution secondary ion mass spectrometry (NanoSIMS) analysis has been performed on longitudinal sections of Alyssum lesbiacum leaves. Elemental maps were obtained which revealed the high concentrations of nickel in the peripheral regions of the large unicellular stellate leaf hairs (trichomes) and in the epidermal cell layer. Electron probe microanalysis (EPMA) was used to provide independent confirmation of elemental distribution in the specimens, but the superior spatial resolution and high chemical sensitivity of the NanoSIMS technique provided a more detailed image of elemental distribution in these biological specimens at the cellular level.     

Combined EPMA and AES depth profiling of a multilayer Ti-Al-O-N coating

In order to compare thin-film electron probe microanalysis (EPMA) and Auger electron spectroscopy (AES) regarding reliability in quantifying chemical compositions of Ti-Al-O-N coatings with depth, a multilayer was prepared on a silicon wafer by using reactive ionized cluster beam deposition technique. Within a total thickness of about 25 nm the composition of the multilayer varied step by step from Ti-Al-O-N at the bottom to Al-O at the top. AES and, as an innovation, EPMA crater edge profiling was applied to measure the composition with depth. For quantification special thin-film EPMA techniques based on Monte Carlo simulations were applied. The chemical binding states of Al and Ti with depth were analysed using a high resolution energy analyser (MAC 3) for the AES investigations working in the direct mode. According to the deposition procedure the concentration profiles of the components varied with depth for both AES and EPMA measurements. AES provided a better depth resolution than EPMA. To get a true calibration of the depth scale an in-situ measurement method like an optical interferometry will be required. Assuming that the relative sensitivity factors are available AES depth profiling delivers concentration profiles with good accuracy. The new EPMA application provided quantitative depth profiles concerning concentration and coverage. For EPMA crater edge profiling the coating needs to be deposited on a foreign substrate because depth distributions of elements being present in both the layer and the substrate cannot be resolved.The combination of AES-depth profiling with EPMA crater edge profiling techniques is a powerful tool to analyse heterostructures quantitatively.     

SiO2/炭泡沫和SiC/炭泡沫复合材料的制备及表征

对炭泡沫为支撑骨架的氧化硅气凝胶(SiO₂/炭泡沫)和碳化硅(SiC/炭泡沫)复合材料分别采用XRD、SEM、激光导热仪、万能力学试验机进行物相、微观结构、热学及力学性能方面的表征。结果表明:所制备的SiO₂/炭泡沫与原炭泡沫相比,具备更高的抗压强度(14.95MPa)和更低的室温热导率(0.44W·m^-1·K^-1)。SiC/炭泡沫材料则保持了较高的抗压强度值(14.66MPa),其在1200℃下具备极低的高温热导率(2.18W·m^-1·K^-1)。热重分析表明,SiC/炭泡沫在氧化氛围中到610℃才发生质量的损失,而内部炭发生完全烧蚀的温度高达844℃,这表明该材料的抗氧化性能远好于纯的炭泡沫材料。     

Investigation on the corrosion of brazed joints by means of scanning auger microprobe

As a model experiment for the corrosion behaviour of brazed joints in water pipes made of stainless steel, some tens ofan broad joints made of three different brazes (Ag/Cu/In/Ni, Ag/Cu/Sn, Ag/Cu) were exposed to streaming water at different Cl^– concentrations. The samples were polarized. The three-dimensional distribution of the corrosion products, obtained by Auger mapping and depth profiling, supplied some information about the corrosion behaviour of the joints.     

SiO2/炭泡沫和SiC/炭泡沫复合材料的制备及表征

对炭泡沫为支撑骨架的氧化硅气凝胶(SiO₂/炭泡沫)和碳化硅(SiC/炭泡沫)复合材料分别采用XRD、SEM、激光导热仪、万能力学试验机进行物相、微观结构、热学及力学性能方面的表征.结果表明:所制备的SiO₂/炭泡沫与原炭泡沫相比,具备更高的抗压强度(14.95 MPa)和更低的室温热导率(0.44 W·m^-1·K^-1).SiC/炭泡沫材料则保持了较高的抗压强度值(14.66 MPa),其在 1 200 ℃下具备极低的高温热导率(2.18W·m^-1·K^-1).热重分析表明,SiC/炭泡沫在氧化氛围中到610 ℃才发生质量的损失,而内部炭发生完全烧蚀的温度高达844 ℃,这表明该材料的抗氧化性能远好于纯的炭泡沫材料.