The development and characteristics of a high-speed EELS mapping system for a dedicated STEM
1 Hitachi High-Technologies Corp., 882 Ichige, Hitachinaka, Ibaraki 312-8504, Japan
2 Hitachi High Technologies America, Inc., 5100 Franklin Drive, Pleasanton, CA 94588, USA
3 Hitachi Research Lab., Hitachi Ltd., 711 Ohmika, Hitachi, Ibaraki 319-1292 and
4 Kogakuin-University, 1-24-2 Nishi Shinjuku, Shinjuku, Tokyo 163-8677, Japan
* To whom correspondence should be addressed. E-mail: baban{at}cc.kogakuin.ac.jp
A new EELS (electron energy loss spectroscopy) real-time elemental mapping system has been developed for a dedicated scanning transmission electron microscope (STEM). The previous two-window-based jump-ratio system has been improved by a three-window-based system. It is shown here that the three-window imaging method has less artificial intensity in elemental maps than the two-window-based method. Using the new three-window system, the dependence of spatial resolution on the energy window width was studied experimentally and also compared with TEM-based EELS. Here it is shown experimentally that the spatial resolution of STEM-based EELS is independent of the energy window width in a range from 10 eV to 60 eV.
Keywords electron energy loss spectroscopy (EELS), scanning transmission electron microscope (STEM), elemental mapping, spatial resolution, ratio map image, three-window method, EELS imaging
Received 14 May 2007, accepted 7 January 2008