Field Emission Auger Electron Spectroscopy with Scanning Auger Microscopy

NREL uses Auger electron spectroscopy (AES) for elemental surface analysis, depth profiling, small feature analysis, and imaging.

How It Works

In AES, we bombard a sample surface with a focused beam of high-energy (2- to 10-kV) electrons.The incident electrons lose energy to the sample atoms, generating Auger electrons that have discrete kinetic energies characteristic of the emitting atoms.

This technique is particularly useful for determining the elemental composition of the surface because Auger electrons have a limited escape depth. A key capability of the field emission AES is its ability to focus the electron beam to a small spot, with resolutions similar to an electron microscope. By scanning the electron beam across the surface, we can generate both element-specific Auger maps and secondary-electron microscope (SEM) images from the same region of the sample.

Applications

Elemental Surface Analysis

Identifies and quantifies elemental compositions of solid surfaces, with a sensitivity to 0.5 at.% for elements from lithium to uranium.

Depth Profiling

Removes successive layers by using argon ions, which allows elemental analysis as a function of depth. Especially useful for quantitative bulk and volumetric analysis of thin-film materials, and for exploring impurities and diffusion present at junctions and grain boundaries.

Small-Feature Analysis

Explores the composition and structure of small particles or intricate features like microelectronics or polycrystalline thin-films with the field-emission electron source. The field-emission electron source produces an exceptionally useful small spot size (> ~25 nm).

Imaging

Obtains SEM micrographs with up to 20,000x magnification by using raster scanning with a highly focused electron beam ≥25 nm in diameter. Using the same raster scan, SAM can produce elemental composition maps of a surface.

Contact