Journal of Electron Microscopy Advance Access published online on August 27, 2009
Journal of Electron Microscopy, doi:10.1093/jmicro/dfp043
Microcalorimeter-type energy dispersive X-ray spectrometer for a transmission electron microscope
1 Advanced Nano-Characterization Center, National Institute for Materials Science, 1-1 Namiki, Tsukuba, Ibaraki 305-0044
2 SII NanoTechnology Inc., 36-1 Takenoshita, Oyama, Sunto, Shizuoka 410-1393
3 Department of Applied Quantum Physics and Nuclear Engineering, School of Engineering, Kyushu University, 744 Motooka, Nishi-ku, Fukuoka, Fukuoka 819-0395
4 High Energy Astrophysics, Institute of Space and Astronautical Science, Japan Aerospace Exploration Agency, 3-1-1 Yoshinodai, Sagamihara, Kanagawa 229-8510
5 JEOL Ltd., 3-1-2 Musashino, Akishima, Tokyo 196-8558
6 Taiyo Nippon Sanso Corp., 10 Okubo, Tsukuba, Ibaraki 300-2611, Japan
* To whom correspondence should be addressed. E-mail: HARA.Toru{at}nims.go.jp
A new energy dispersive X-ray spectrometer (EDS) with a microcalorimeter detector equipped with a transmission electron microscope (TEM) has been developed for high- accuracy compositional analysis in the nanoscale. A superconducting transition-edge-sensor-type microcalorimeter is applied as the detector. A cryogen-free cooling system, which consists of a mechanical and a dilution refrigerator, is selected to achieve long-term temperature stability. In order to mount these detector and refrigerators on a TEM, the cooling system is specially designed such that these two refrigerators are separated. Also, the detector position and arrangement are carefully designed to avoid adverse affects between the superconductor detector and the TEM lens system. Using the developed EDS system, at present, an energy resolution of 21.92 eV full-width-at-half maximum has been achieved at the Cr K
line. This value is about seven times better than that of the current typical commercial Si(Li) detector, which is usually around 140 eV. The developed microcalorimeter EDS system can measure a wide energy range, 1–20 keV, at one time with this high energy resolution that can resolve peaks from most of the elements. Although several further developments will be needed to enable practical use, highly accurate compositional analysis with high energy resolution will be realized by this microcalorimeter EDS system.
Keywords EDS, TEM, transition-edge sensor, microcalorimeter, high energy resolution, cryogen-free cooling system
Received 19 May 2009, accepted 4 August 2009