Elemental mapping at the atomic-level is now possible across the periodic table using X-ray spectroscopy techniques
FEI Company, a leading instrumentation company providing systems for research and industry, has announced that it is extending its ChemiSTEM Technology to enable, for the first time, atomic-level energy dispersive X-ray (EDX) spectroscopy across the periodic table. The combination of increased current in an atomic-sized probe by Cs-correction and the increase in X-ray detection sensitivity and beam current of the ChemiSTEM technology allows results to be obtained within minutes.
“The powerful combination of the groundbreaking ChemiSTEM technology and an aberration corrector offers unique capabilities for materials science,” said Professor Ferdinand Hofer of Graz University of Technology, Austria. “One of the most important applications for the new technology will be element-specific imaging at atomic resolution. We will apply the technology to study interfaces in semiconductors, solar cell materials, LEDs and ceramic materials with previously unknown detection sensitivity and accuracy.”
George Scholes, FEI’s vice president for product management, adds, “The ChemiSTEM Technology will enable breakthrough results in many key application areas for our customers, such as catalysis, metallurgy, microelectronics, and green energy materials, to name a few. For example, in a recent experiment with ChemiSTEM technology, our customer was able to clearly resolve the core-shell structure of 5 nm catalyst nanoparticles in about three minutes and with three times greater pixel resolution than a previous experiment with conventional technology. And the conventional technology failed after three hours of data collection to clearly resolve the same structure.”
ChemiSTEM technology achieves a factor of 50 or more enhancement in speed of EDX elemental mapping on scanning/transmission electron microscopes (S/TEMs) compared to conventional technology employing standard EDX silicon-drift detectors (SDDs) and standard Schottky-FEG electron sources. It combines FEI’s proprietary X-FEG high brightness electron source, providing up to five times more beam current at a given spatial resolution, the patent-pending Super-X detection system, providing up to ten times or more detection sensitivity in EDX, and fast scanning electronics, capable of achieving EDX spectral rates of up to 100,000 spectra per second. Additionally, the windowless detector design employed for each of ChemiSTEM technology’s four integrated SDD detectors has proven to optimize the detection of both light and heavy elements.
This combination of high detection sensitivity and high spectral rates of up to 100,000 spectra per second are enabling better EDX mapping of materials that are highly sensitive to electron beam damage, such as composition analysis in nanometer-scale indium gallium nitride quantum wells used in light-emitting diode (LED) devices, and semiconductor devices with potentially mobile dopant materials, as well as many others devices used in emerging nanotechnologies.
For more information about ChemiSTEM Technology, visit: www.fei.com/chemistem
Caption: The images show atomic-level EDX spectroscopy of the material strontium titanate; the individual atomic positions of the crystal structure can be easily distinguished by their chemical signal (red is strontium, green is titanium). These images are based on raw data, with no signal post-processing, and the individual atomic column positions in the structure are visible and clearly distinguished from their neighbors with very high contrast and signal-to-noise quality. The sampling of these atomic-level chemical maps is 0.075 angstroms per pixel, the highest sampling density obtained so far by any atomic spectroscopy technique using scanning/transmission electron microscopy (S/TEM). These chemical maps were acquired in just minutes on a Titan G2 60-300 S/TEM with ChemiSTEM technology.
