Emploi quantitatif de la spectroscopie Auger; Étalonnage de la méthode

A calibration is presented for the measurement, by Auger electron spectroscopy, of sulphur adsorbed on nickel. The Auger emission from the metal is used as a reference. The use of radioactive sulphur permits a direct measurement of the quantity of adsorbed sulphur.     

Beobachtung von Elektronen-Channeling-Diagrammen im Augerelektronen-Spektrometer mit Rasterzusatz

In the scanning electron microscope the electron channeling patterns allow us to determine the orientation and quality of single crystal objects. If the Auger spectrometer is equipped with a scanning sample positioner, the electron channeling patterns can be observed with primary energies used in Auger spectroscopy, i.e. 0.5–5 keV.     

On the restoration of Auger line shapes

A simple and efficient method to deduce the true Auger spectrum from the raw data is presented. This method is an application to Auger spectroscopy derived from signal processing procedures employed in different fields. It appears particularly promising when complex spectra are analyzed as it avoids spurious information to be introduced. The method is also compared with the more-standard van Cittert's approach. An experimental check of the common assumption that an Auger electron experiences almost the same energy-loss mechanisms as a nearly elastically reflected primary electron at the same energy is given.     

Crystallographic incident beam effects in quantitative Auger electron spectroscopy

Auger electron spectroscopic studies of cylindrical copper single crystals show large variations with surface orientation in Auger yield from both the clean surface and oxygen adsorbed to saturation on the surface which can be attributed to incident beam effects and “inverse Kikuchi” phenomena. Ways are discussed of minimising the effect of these anisotropies to obtain true comparative surface coverages from Auger electron spectroscopy of different crystal surface orientations.     

Auger and direct electron spectra in X-ray photoelectron studies of zinc,zinc oxide,gallium and gallium oxide

Auger and direct electron spectra from Zn, ZnO, Ga and Ga₂O₃ have been studied with X-ray photoelectron spectroscopy (ESCA). The chemical shift between zinc electron binding energies in Zn and ZnO is very small, whereas the zinc Auger electron signals are separated by 4.3 eV. In gallium, the oxide and metal signals are separated by 1.9 eV, but the Auger electron energy shift is three times as large. Thus the Auger signals are more sensitive to the chemical environment than the direct electron signals, which is the same relation as earlier observed for copper and copper oxides.     

Photoemission measurements of bulk,surface and hydrogen induced states on cleaved Ge(111)

Ultraviolet photoemission spectroscopy using HeI (21.2 eV) resonance photons has been used to study cleaved Ge(111) surfaces which were also characterized by Auger electron spectroscopy and low energy electron diffraction. Higher effective resolution for both bulk and surface states was found than for recent measurements employing synchrotron radiation.     

The growth mode of aluminium on silver (111)

The geometric and electronic structures occuring during the growth of Al on a single crystal Ag(111) surface have been studied using a combination of low energy electron diffraction (LEED), Auger electron spectroscopy (AES), energy loss spectroscopy (ELS) and work function measurements. The Auger signal versus deposition time plots, which were used to monitor the growth mode, are shown to behave in an identical fashion to that expected for layer-by-layer (Frank-van der Merwe) growth. LEED was used to determine the lateral periodicity of thin Al films and shows that Al forms, at very small coverages, 2D islands which have the same structure as the Ag(111) substrate and which grow together to form the first monolayer. At substrate temperatures of 150 K a well defined (1 × 1) structure with the same orientation as the underlying Ag(111) can be seen up to at least 12 ML. After completion of the third monolayer the ELS spectrum approached that observed for bulk aluminium. At a coverage of 3 ML the work function decreases by 0.4 eV from the clean silver value.     

Angular-resolved photoemission from GaAs(110) surfaces with adsorbed Al

GaAs(110) surfaces with adsorbed Al were studied by a combination of angular-resolved valence band photoemission, Ga 3d core level photoemission, low energy electron loss spectroscopy and Auger electron spectroscopy. At room temperature Al is adsorbed on top of GaAs. After heat treatment the compound AlAs is formed at the surface, which is used as a substrate for Ga adsorption to form the inverted structure of the system GaAs + Al.     

Energy and angular distributions of electrons emitted by direct double auger decay

We have observed the direct L(2,3)MMM double Auger transition after photoionization of the 2p shell of argon by angle-resolved electron-electron coincidence spectroscopy. The process is responsible for about 20% of the observed Auger electron intensity. In contrast to the normal Auger lines, the spectra in double Auger decay show a continuous intensity distribution. The energy and angular distributions of the emitted electrons allow one to obtain information on the electron correlations giving rise to the double Auger process as well as the symmetry of the associated two-electron continuum state.     

Investigation of ageing characteristics and identification of surface chemical changes on SrGa2S4:Ce display phosphor under electron beam bombardment

Cathodoluminescent ageing characteristics of SrGa₂S₄:Ce³⁺ under prolonged electron beam bombardment was studied and the data are presented. The cathodoluminescent intensity with an increasing Coulomb loading was observed to degrade under different primary electron beam voltages. Auger electron spectroscopy (AES) and X-ray photoelectron spectroscopy (XPS) were used to monitor the surface chemical changes during electron beam bombardment and after the degradation process. Auger peak to peak heights monitored during the ageing process suggest a loss in S and C and an initial increase in oxygen concentration on the surface. XPS results indicate the formation of a SrO overlayer due to electron stimulated surface chemical reactions (ESSCRs).     

Structural studies of clean and overlayered surfaces with an application to xe adsorption on Ag

Low-energy electrons have a particularly important role in many of the techniques of surface science. In some experiments, such as low-energy electron diffraction and characteristic loss spectroscopy, they are scattered either elastically or inelastically; in others, such as electron-stimulated desorption, they are used to produce excitations of the surface; and in still others, the resident electrons are excited to energies where they may escape from the material, as in photoemission, Auger, and ion neutralization spectroscopy. The reason for this central role is that, of all the physical probes, the electron is the simplest one that interacts strongly enough to be sensitive to the last few layers of atoms.     

氧化物薄膜研制中的电子能谱技术

随着科学技术的不断发展，人们正在寻求更新的实用材料．金属氧化物，包括金属氧化物薄膜的各种实用材料，在工业界、信息产业界和能源开发等方面的应用前景，早已引起国内外学者的极大关注．例如，由于氧化物具有各种特殊的介电和光学性质，研究和开发基于氧化物薄膜的气敏材料非常热门．如何制备出有实用价值的各种薄膜材料，是科学家们一直关心和深入研究的课题．电子能谱技术在各种材料的基础研究和实际应用中起着重要的作用．本文以有序金属氧化物薄膜研制为例，简要评述了电子能谱技术（包括X射线光电子能谱（XPS），紫外光电子能谱（UPS），俄歇电子能谱（AES）和高分辨电子能量损失谱（HREELS）），以及低能电子衍射（LEED）等技术在氧化物薄膜材料制备和表征中的应用．     

Characteristics of sputtered Ta-B-N thin films as diffusion barriers between copper and silicon

Ta-B-N thin films were prepared by rf-magnetron sputtering from a TaB₂ target in N₂/Ar reactive gas mixtures and then used as diffusion barriers between Cu and Si substrates. In order to investigate the performance of Cu/Ta-B-N/Si contact systems, X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), four-point probe measurement, scanning electron microscopy (SEM), cross-sectional transmission electron microscopy (XTEM), and Auger electron spectroscopy (AES) depth profile were used. Results of this study indicate that the barrier characteristics are significantly affected by the nitrogen content. In addition, the failure mechanism for the Cu/Ta-B-N/Si contact systems is also discussed herein.     

超高真空俄歇电子能谱原位加热和GaN热效应研究

建立一套基于超高真空俄歇电子能谱的原位加热系统,对GaN薄膜进行热效应研究．随着温度的增加,Ga LMM和Ga MVV的动能减小．利用第一性原理计算,获得理论的GaMVV俄歇谱.加热过程由于晶格热膨胀以及表面原子再构引起价电子态密度发生变化,从而导致价带俄歇谱负移．     

Quantitative Auger electron spectroscopy analysis of binary alloys with separate matrix correction factors for bulk and surface

A new method which takes into account the separate matrix correction factors for bulk and surface has been tried out for quantitative Auger electron spectroscopy analysis of binary alloys. The calculations use an iteration scheme. It has been applied to the Fe-Cr alloys studied at this Centre and the Auger electron spectroscopy data for the other alloy systems available in literature. The results are now more compatible with the expectation that the surface composition is different from the bulk.     

Comparison of escape depths between Auger electron and disappearance potential spectroscopy electron

The escape depths of the characteristic electrons of the Auger electron and the quasielastically reflected electron were determined by Auger electron spectroscopy (AES) and disappearance potential spectroscopy (DAPS), respectively, for a Cr overlayer onto Ti and Fe substrates. For the case of Cr on Fe, in-situ measurements of AES and DAPS were carried out. From the results, the mean free paths of 455, 575 and 710 eV electrons through Cr were obtained as 9.6, 13 and 15 Å, respectively. The attenuation length of a 2.5 keV primary electron of AES through Cr was also obtained and the value was 62 Å. In addition, the mean free paths of electrons with the same energy depend on the scattering materials of Cr, Mo and W (material dependence). The phenomena are useful for a quantitative electron spectroscopy of surfaces.     

白碳纳米晶薄膜及其场致电子发射特性

利用微波等离子体化学气相沉积方法,以甲烷、氢混合气体为反应气体,具有钛镀层的玻璃作为衬底,制备了具有sp¹杂化结构的白碳纳米晶薄膜。利用X射线衍射、俄歇电子能谱,以及扫描电子显微镜对薄膜结构进行了表征。以白碳纳米晶薄膜为阴极,以镀有ITO透明导电薄膜玻璃为阳极,采用二极管结构,测试了白碳纳米晶薄膜的场致电子发射特性。开启电场为2.5 V/μm,在电场为5 V/μm时的电流密度为200μA/cm²。对白碳纳米晶薄膜生长机理,以及其场致电子发射机制进行了讨论。     

The characterisation of iron-containing intermetallic phases within industrially cast aluminium

⁵⁷Fe conversion electron Mössbauer spectroscopy has been used to investigate the intermetallic phases near the surface of a D.C. cast aluminium ingot. The CEMS data is used with SAAES (selected area Auger electron spectroscopy) and SAXPS (selected area X-ray photoelectron spectroscopy) data to propose a model of the surface region above the grain boundaries.     

Surface segregation in liquid GaSn alloys by AES

The surface segregation of Sn in liquid GaSn alloys has been studied by Auger electron spectroscopy as a function of bulk concentration at 350° C. The Sn was found to be strongly adsorbed at the surface. The surface concentrations of Sn and Ga were calculated from the Auger measurements using inelastic mean free paths and backscattering factors estimated in recent theoretical work. The values found for the surface concentrations are essentially in agreement with those deduced from surface tension measurements using Gibbs adsorption theory. This result supports a monolayer adsorption distribution in the GaSn system.     

Quantitative Auger analysis of ion-implanted boron and arsenic in polycrystalline silicon

Quantitative analysis of boron and arsenic in silicon has been made by Auger electron spectroscopy with the in-situ ion milling technique. Ion-implanted boron and arsenic in polycrystalline silicon was used as standard samples. The experimental results indicate that the semi-empirical formalism for quantitative Auger analysis is valid for impurity concentrations less than a few percent. Excellent linear relationship has been obtained between the implanted dose and the normalized Auger signal intensity within ±10% for boron and ±20% for arsenic in silicon.