Electron-Excited Energy Dispersive X-Ray Spectrometry at High Speed and at High Resolution: Silicon Drift Detectors and Microcalorimeters

Published

October 16, 2008

Author(s)

Dale E. Newbury

Abstract

Two recent developments in x-ray measurement technology provide dramatic improvements in analytical x-ray measurement science that will impact the frontiers of electron microscopy. (1) The silicon drift detector (SDD) uses the same measurement physics (photoelectric absorption, inelastic scattering and charge generation) as the silicon (lithium) energy dispersive x-ray spectrometer [Si(Li) EDS] but is different in design: 10% of the thickness of the Si(Li) EDS with a complex rear surface electrode pattern that imposes a lateral internal charge collection field. For most measures of spectrometric performance, the SDD equals or betters the Si(Li) EDS. In the key performance measure of the out count rate vs. input count rate, the SDD exceeds the Si(Li) EDS by a factor of 5 to 10 for the same resolution. This high throughput can benefit analytical measurements which are x-ray count limited, such as x-ray mapping.(2) The microcalorimeter EDS determines the energy of an x-ray by measuring the temperature rise in a metal absorber. Operating at 100 mK, the microcalorimeter EDS achieves resolution of 2 5 eV over a photon energy range of 200 eV to 10 keV in energy dispersive operation. This high resolution enables resolution of most peak interference situations and provides a high peak-to-background to detect low fluorescence yield peaks. This resolution is also sufficient to distinguish chemical (bonding) effects on low energy x-ray photons less than 2 keV in energy.

Citation

Microscopy and Microanalysis

Pub Type

Journals

Keywords

electron microscopy, energy dispersive spectrometry, microcalorimeter, scanning electron microscopy, silicon drift detector, wavelength dispersive spectrometry

Citation

Newbury, D. (2008), Electron-Excited Energy Dispersive X-Ray Spectrometry at High Speed and at High Resolution: Silicon Drift Detectors and Microcalorimeters, Microscopy and Microanalysis (Accessed April 25, 2024)