Auger Scanning Electron Microscopy Research Articles

Surface analytical scanning electron microscopy in ultrahigh vacuum combined with scanning tunnelling microscopy

AbstractA scanning electron microscope of ultrahigh vacuum with a field emission gun is operated at primary energies in the range 100 eV to 3 keV. The instrument can form the images that contain information on surface chemical composition, chemical bonding state (electronic structure) and surface crystal structure at a microscopic resolution of several hundred angstroms (Å) using the techniques of scanning Auger electron microscopy, scanning electron energy‐loss microscopy and scanning low‐energy electron diffraction (LEED) microscopy. Scanning tunnelling microscopy (STM) also has been combined with a SEM in order to obtain the atomic resolution for the solid surface.The instrumentation and examples of their applications are presented both for scanning LEED microscopy and STM.

Surface precipitation of boron nitride on the surface of stainless steel/boron nitride film

A mixture of type 304 stainless steel and boron nitride was deposited on the surface of type 304 substrate which a r.f. magnetron sputtering method. Scanning Auger electron microscopy and X-ray photoelectron spectroscopy observation showed that boron nitride precipitated on the surface of the deposited film and the precipitated boron nitride uniformly covered the surface after annealing at more than 600 K in high vacuum. Only small carbon and oxygen Auger peaks were observed on the surface of the preciptated boron nitride after the 3.6 ks (= 1 hour) exposure in air indicating that the surface of this film covered with boron nitride was inert to gas adsorption. Therefore, the film of the mixture of stainless steel and boron nitride can be a candidate material for surface modification of vacuum vessels.

Scatter diagrams and hotelling transforms: application to surface analytical microscopy

The collection of electrons from several Auger peaks together with other electrons scattered from a sample in a scanning Auger electron microscope provides a means of analysing many features of an inhomogeneous surface. The use of multi-image sets in the analysis of samples of Al on Si, W on Si, LaNi compounds and superconducting wires are given as examples. The use of scatter diagrams as a means of classifying the number and coverage of different surface phases is illustrated. The Hotelling transform is described and then applied both to data from a real W/Si sample and to simulated images which are chosen to illustrate the ways in which this transform can be useful. The design of a new 23 channel Auger microscope intended to take advantage of the multi-spectral approach to data acquisition is outlined.

Work function spectroscopy as a tool for thin film analysis

Work function measurements are known to provide important information on the structural and chemical conditions of surfaces and interfaces. Lateral and depth-dependent variations in the work function can be determined in an electron beam scanning mode by measuring locally the onset energy of the secondary electron energy distributions, e.g. in a scanning Auger microprobe. Corresponding studies have been performed for a polycrystalline aluminium surface and an NiCr multilayer system. The potentialities of work function scanning microscopy as a novel analytical technique are demonstrated by resolving the structure of small impurity particles in thin sublayers. Although work function spectroscopy does not provide direct chemical information, it has proved to be a very useful technique especially in conjunction with scanning Auger or scanning electron microscopy.

Analytical scanning electron microscopy for solid surface.

A scanning electron microscope of ultra-high-vacuum (UHV-SEM) with a field emission gun (FEG) is operated at the primary electron energies of from 100 eV to 3 keV. The instrument can form the images that contain information on surface chemical composition, chemical bonding state (electronic structure), and surface crystal structure in a microscopic resolution of several hundred angstroms (A) using the techniques of scanning Auger electron microscope, scanning electron energy loss microscope, and scanning low-energy electron diffraction (LEED) microscope. A scanning tunneling microscope (STM) also has been combined with the SEM in order to obtain the atomic resolution for the solid surface. The instrumentation and examples of their applications are presented both for scanning LEED microscopy and STM.

Sensitization of inconel 600. I. Scanning auger and optical microscopy

Abstract The effect of impurity elements such as carbon, phosphorus, boron and silicon on the microstructural characteristics and grain-boundary chemistry of Inconel 600 has been investigated using optical microscopy and scanning Auger electron microscopy techniques. Of the elements added, only phosphorus was detected at grain boundaries and at the carbide-matrix interface. Carbon and boron were found to form discrete precipitates while silicon did not affect significantly the microstructural characteristics of the material. Sulphur-rich particles were found at the fractured surfaces and were associated with chromium carbides and titanium nitrides.

Analytical Scanning Electron Microscopy for Solid Surface

A scanning electron microscope of ultra-high-vacuum (UHV-SEM) with a field emission gun (FEG) is operated at the primary electron energies of from 100 eV to 3 keV. The instrument can form the images that contain information on surface chemical composition, chemical bonding state (electronic structure), and surface crystal structure in a microscopic resolution of several hundred angstroms (A) using the techniques of scanning Auger electron microscope, scanning electron energy loss microscope, and scanning low-energy electron diffraction (LEED) microscope. A scanning tunneling microscope (STM) also has been combined with the SEM in order to obtain the atomic resolution for the solid surface. The instrumentation and examples of their applications are presented both for scanning LEED microscopy and STM.

XPS and SAM study of the high T c superconductor YBa 2Cu 3O 7− x

The binding states of Y, Ba, Cu, and O in YBa 2Cu 3O 7− x were studied by X-ray photoelectron spectroscopy (XPS). The binding energy of Y corresponds to that of yttrium oxide (Y 2O 3). Deconvolution of the O 1s and C is XPS spectra in conjunction with the Ba 3d peak allow a clear distinction between Ba in a normal 2 + oxide state and in a carbonate (BaCO 3). Indication for the presence of carbon, probably due to unreacted from the starting material BaCO 3, is also found by chemical analysis and by Auger electron microscopy. XPS analysis at the surface allowed the determination of Cu 1+, Cu 2+, and Cu 3+ binding states. Scanning Auger electron microscopy (SAM) reveals a inhomogenous surface composition.

Nature of indigenous sulfur segregated to the free metal surface and to the scale-metal interface

Sulfur segregation to the free metal surface of a Ni-20(wt.%)Cr-12(wt.%)Al alloy has been documented by high-temperature scanning Auger electron microscopy. Preferential enrichment of sulfur occurs to the surface of the chromium-rich γ phase in the two-phase y nickel-β (NiAl) alloy. Electron spectroscopy for chemical analysis (ESCA) studies have indicated that for a free metal surface, i.e., metal without an overlying thermally grown oxide scale, the surface segregated sulfur correlated with both S−2 and elemental sulfur. Energy-dispersive X-ray analysis (EDAX) characterization of fractured oxide films thermally grown on the Ni-Cr-Al alloy indicated that both a labile, i.e., relatively volatile, and a refractory sulfur species exist at the scale-metal interface. Elemental sulfur as detected by ESCA has the volatility characteristics found for the labile sulfur species found in the scanning electron microscopy (SEM)-EDAX studies.

走査型オージェ電子分光装置によるＡｕ‐Ｃｕ合金表面組成分析

走査型オージェ電子分光装置によるＡｕ‐Ｃｕ合金表面組成分析

Continuous observation of the ion sputtering of metal surfaces in SEM.

A continuous observation of the metal surfaces has been performed by using a SAM (scanning Auger electron microscope, an Auger version of SEM) to study the ion sputtering phenomena, such as preferential sputtering, a cone formation, and other morphological changes. A 16-mm movie technique and a particular time sequence method for the ion sputtering were introduced to the SAM system. Some applications of the technique to the pure metals (Cu) and alloys (Cu-Sn and Pb-Sn) are demonstrated. It was found that some phenomena characteristic to the ion sputtering can be revealed only with this technique.

Scanning Auger electron microscope resolution determined by a quantitative AES method

In quantitative Auger electron spectroscopy (AES) analysis, the emphasis is generally laid on the vertical variation in signal from an element versus the variation in composition from the surface to the bulk. In such a framework, a quantitative method has been previously developed by the authors, which provides such information as the thickness of a segregated layer or the initial growth process of a thin film. Here, this method is applied to study a horizontal variation of composition, i.e. the signal variation of a scanning Auger electron microscope (SAM) when the incident electron beam is scanned across the boundary of grains of different composition. In order to evaluate the SAM resolution, for the case of an ideal step boundary, calculations are carried out by taking into account the influence of angular distributions, of attenuation length of primary, secondary and Auger electrons, of secondary electron yield and of the beam shape (point, Gaussian or columnar). The results for the cases of Ag-Au, Si-Ag and Be-Cu, lead to a SAM spatial resolution of ≈30 Å for a primary beam of 2–3 keV with an infinitesimal diameter and a resolution of the order of the beam size for Gaussian and columnar beams. Extrapolation of this method to a primary beam energy of 20 keV is discussed and leads to results similar to those obtained by Monte Carlo simulation.

Scale formation in coal liquefaction reactor using FeS catalysts

The origin and formation behavior of scale in a coal liquefaction reactor, in which disposable catalysts such as red mud-sulfur were used, has been investigated by means of model experiments. The scale formed in the continuous coal liquefaction reactor which operated at a throughput of 0.1 t/d was analyzed with an electron probe microanalyzer (EPMA), scanning electron microscope (SEM), X-ray and scanning Auger electron microscope (SAM) techniques. It was observed in the model experiments that the scale formed on the surface of stainless steel (SUS-316) at temperatures higher than 250°C. The amount of scale formed was found to depend on the reaction temperature, the exposure time and the sulfur content of the catalyst. The scale formed in the continuous reactor collected on the walls of the tube, preheater and reactor. It was found that the scale was derived from two sources, the coal paste (catalyst, inorganic components in coal and unreacted coal) and the sulfidation of reactor materials.

Scanning Auger electron microscope resolution determined by a quantitative AES method

Scanning Auger electron microscope resolution determined by a quantitative AES method

Scanning Auger electron microscope resolution determined by a quantitative AES method

Scanning Auger electron microscope resolution determined by a quantitative AES method

Tests of surface segregation theory II. The Cu-10Pd alloy

Annealed polycrystalline specimens of the alloy Cu-10Pd (at%) have been examined in a scanning Auger electron microscope (SAM). After prolonged heating and exposure to oxygen, to remove bulk impurities, the clean equilibrated surfaces were observed for the temperature range 920 to 1280 K and were found to be enriched in Cu compared to the bulk composition. This is in qualitative agreement with the predicted behaviour of this alloy if it is taken that the driving forces for segregation are the relief of bulk lattice strain and the reduction of the surface free energy. Using the imaging facilities of the SAM, including computer post-acquisition processing of multiple registered Auger images, quantitative compositional maps were produced. Due allowance was made for the sometimes misleading effects of incident electron beam channelling upon quantitative Auger analysis of crystalline specimens by comparing data collected at several angles of incidence for each surface studied. The quantitative images showed a marked variation in surface composition from grain-to-grain for each temperature and also a corresponding variation in the heat of segregation between 0 and -15 kJ mol -1. The surface composition averaged over many grains was temperature dependent with a surface average value of the heat of segragation of ca.-6 kJ mol -1. This value is in close agreement with that quoted elsewhere but is shown here to be inconsistent with simple theoretical expressions for describing the surface segregation.

A Micro-Quantitative AES Analysis Using SEM-SAM Apparatus (Applied to Ag/Si Interfaces on Si(111) and Si(100) Surfaces)

Two kinds of samples were prepared in order to analyze the Ag/Si interfaces on Si (111) and Si (100) surfaces. Type 1: Ag films were deposited on Si (111) and Si (100) at higher substrate temperatures (300∼400°C). Type 2: Ag films were first deposited on Si (111) and Si (100) substrates at room temperature and heat treated thereafter at higher substrate temperatures (300∼400°C). These prepared samples were observed using high-resolution scanning electron microscope and scanning Auger electron microscope (SEM-SAM) equipment. Then, the Auger electron spectroscopy (AES) data from a micro-point analysis were analyzed by a newly developed quantitative AES method. The results show that about one monolayer of Ag grows on both the Si (111) and Si (100) surfaces and Ag islands grow thereafter (Stranski-Krastanov mode). Further, an averaged Ag island size near saturation was about 1 µm on Si (100) and its density was about 10-times larger than that on Si (111).

Techniques for the correction of topographical effects in scanning Auger electron microscopy: M Prutton et al,J Appl Phys, 54 (1), 1983, 374–381

Techniques for the correction of topographical effects in scanning Auger electron microscopy: M Prutton et al,J Appl Phys, 54 (1), 1983, 374–381

Application of AES, SAM, EPMA, XPS and UPS to study of interface.

Principles of AES (Auger Electron Spectroscopy), SAM (Scanning Auger electron Microscope), EPMA (Electron Probe Micro Analyzer), XPS (X-ray Photoelectron Spectroscopy), and UPS (Ultraviolet Photoelectron Spectroscopy) are briefly described. Examples for study of interface using these techniques are also described. Advantages, disadvantages and limitations of these are pointed out.

Dynamic observation of surfaces by scanning Auger electron microscopy: A motion picture technique

The dynamic observation of surfaces has been developed by using a scanning Auger electron microscope (SAM). The images of Auger and secondary electrons are photographed continuously with a 16-mm movie camera. Each frame is photographed for very short time exposures of 24 to 48 s for the Auger and 3 s for the secondary electrons. Particular logic circuits to control the system were made providing for the rejection of the secondary electrons ejected by the ions and for the photons from the filament of the ion gun which greatly degrade the images.