Auger Electron Spectroscopy (AES) Analysis Laboratory

Auger Analysis, Auger Electron Spectroscopy (AES or Auger) is a chemical surface analysis method. AES measures the chemical composition of the outermost 100 Å of a sample. Measurements can be made at greater depths by ion sputter etching to remove surface layers.

All elements except for H and He can be detected at concentrations above 0.1 to 1.0 atom %, depending on the element. In addition, elemental concentration versus depth (up to 2 µm) information can be obtained by ion sputter etching while monitoring every element of interest. Only conductive samples can be measured with this technique. The sampled area varies from 1 mm down to 2 µm in diameter.

Scanning Auger Techniques

Auger Electron Spectroscopy (AES Analysis), also referred to as Scanning Auger Microscopy (SAM), uses a focused electron beam to create Auger electrons near the surface of a solid sample. These electrons have energies characteristic of the elements and, in some cases, chemical bonding of the atoms in the sample. AES can provide elemental maps, and when combined with sputtering, gives elemental and chemical information as a function of depth (depth profiling). Due to the nature of the Auger electron emission process, AES can detect all elements except H and He. It is usually nondestructive, except when depth profiling. Concentrations as low as 0.1 atom% can be detected. The sampling depth is 15-30 monolayers (50-100Å) and it can distinguish features as small as 0.1 µm, AES dos elemental analysis of unknown conductive materials well.

Scanning Auger Microprobes

Our Physical Electronics Mode 610 Scanning Auger Microprobe provides scanning Auger microscopy (SAM), Auger electron spectroscopy (AES), and secondary ion mass spectrometry (SIMS). The system uses AES to perform compositional analysis and compositional depth profiling of selected elements by recording the Auger intensities as a function of energy or sputtering time, respectively. SAM uses AES in a raster scanning mode to provide an image of the lateral distribution of elements on the sample surface. SIMS detects secondary ions sputtered from the surface to identify elements or molecular species by their mass-to-charge rations. SIMS analyses can be performed in either static or dynamic mode.

The Model 610 is often used in cases where fine x-y spatial resolution (300Å) is needed. The Model 610 can operate at lower current levels than other electron beam instruments. This is advantageous when analyzing nonconductive samples. Additionally, the system has EBIC (electron beam induced current), EBIV (electron beam induced voltage) and AVC (Auger voltage contrast) functions for performing microelectrical analysis.

Auger Electron Spectra

Auger spectra identify surface constituents or determine the composition of specific surface features. Spectra can be generated in two ways: the point analysis mode, where a stationary beam probes a selected point, or the area-averaged mode where the beam is rastered over the surface. With either method, spectral data are collected and stored in the N(E) format, i.e., the electron energy analyzer is stepped through a selected energy range and the electron signal level at each step is measured and stored. It can be scanned repetitively to obtain the desired signal level. Mathematical routines such as differentiation, smoothing, expansion and background subtraction can then be applied to the stored data. A multiplex format, where selected energy regions containing Auger peaks of interest are scanned, is also available. It is used for automatic data acquisition and quantification, e.g., sputter depth profiling, using computer routines and elemental sensitivity factors derived from standards. Auger analysis performed simultaneously with ion beam sputter etching provides information on elemental composition as a function of depth into the material and is termed “compositional depth profiling.”

Auger Line Scans

An Auger line scan shows the relative concentration of a specific element along a line across the specimen. The electron beam is stepped point-by-point along a selected line. The Auger peak height and background level are measured and the difference stored. The system can scan up to five vertical or horizontal lines and will monitor up to ten elements per line in a single sequence. Stored data can be printed or superimposed on a photomicrograph. Line scans can also be corrected for topography using a special computer algorithm.

Auger Compositional Maps

An Auger image, or elemental map, shows the surface distribution of an element. An elemental map is obtained by setting the analyzer to a specific Auger peak energy and scanning the electron beam over the selected sample area point-by-point. The peak intensity above the adjacent background at each point is measured and stored for later output. The matrix size a s specified by the operator can be up to 250 lines with up to 250 points per line. The stored image can be photographed with a 4-to 256-level gray-scale format or a pseudo-color format.

Auger Line-Shape Analysis

Auger line-shape analysis involves the resolution of observed changes in KVV, LVV, MVV, NVV Auger transitions due to different chemical environments in a material. AES data is recorded in N(E) mode and corrected for secondary electron background as well as inelastic backscatter. Curve fitting is then accomplished by using a weighted-least-squares fit of a Gaussian function to the data values by means of stepwise Gauss-Newton iterations. A Gaussian fit to the actual data is used since the data are taken in a pulse count mode and the pulse-height distribution is Gaussian. In most cases, theoretical Auger line shapes are used as models for the curve fit parameters.

Auger Voltage Contrast

Auger voltage contrast (AVC) involves the measurement of energy shifts (about 0.5 eV) of Auger transitions associated with an internal potential at a p-n junctions. A narrow energy window is set on the slow-energy slope of an Auger peak while the electron beam is scanned across the sample in the Auger compositional mapping mode. The small energy differences are measured and displayed as a surface potential map of the p-n junction. This technique requires an angle lapped surface to be useful.

Applications

The Auger techniques described above may be applied to a wide range of problems including the study of:

• surface chemistry
• depth profiling
• corrosion
• contamination
• diffusion studies
• grain boundary segregation
• interfacial contamination
• oxide thickness
• layers in digital storage media
• biomaterials
• semiconductors

At Rocky Mountain Laboratories, Inc, we’re at the forefront of surface analysis, offering specialized services in Auger Analysis (Auger Electron Spectroscopy) and AES Analysis (Auger Electron Spectroscopy). These cutting-edge techniques empower you to delve deep into the composition and characteristics of surfaces, enabling precise material characterization and quality control.

Auger Analysis (Auger Electron Spectroscopy):

Auger Analysis is a powerful surface-sensitive technique that provides valuable insights into the elemental composition and chemical state of materials. Our Auger Spectroscopy experts use high-resolution instruments to detect and analyze Auger electrons emitted from the surface, offering:

Elemental Composition: Accurate determination of surface elements, even in trace amounts.
Chemical State Information: Identification of chemical bonding and oxidation states.
Layer Thickness: Measurement of thin film and coating thickness.
Surface Contamination Detection: Identification of contaminants or impurities on surfaces.

AES Analysis (Auger Electron Spectroscopy):

AES Analysis is a complementary technique that enhances the capabilities of Auger Spectroscopy. It provides detailed information about surface elements and their distribution. Our AES Analysis Laboratory offers:

Depth Profiling: Characterization of elemental composition as a function of depth beneath the surface.
Surface Mapping: Visualization of elemental distribution and concentration variations on the surface.
Surface Chemistry: Determination of surface chemical reactions and transformations.

Why Choose Our Auger and AES Analysis Laboratory Services?
Unparalleled Expertise: Our team consists of skilled analysts with extensive experience in Auger and AES Spectroscopy, ensuring the highest-quality results.
State-of-the-Art Instruments: We invest in the latest instrumentation to provide you with the most accurate and reliable data.
Cross-Industry Applications: Our services cater to a wide range of industries, including semiconductor, materials science, aerospace, and more.
Customized Solutions: We tailor our analysis approaches to meet your specific research, quality control, and development needs.
Confidentiality: Your data is treated with the utmost confidentiality and security.

Experience Precision Surface Analysis

Harness the power of Auger and AES Analysis to gain a deeper understanding of your materials’ surface characteristics. Whether you’re exploring new materials, troubleshooting surface issues, or conducting quality control, our services provide the insights you need.