Seminars

Physics Seminar: High Resolution Imaging and X-Ray Microanalysis in the FE-SEM


Speaker: Dr. Raynald Gauvin, Department of Materials Engineering, McGill University, Montréal, Canada

Title: "High Resolution Imaging and X-Ray Microanalysis in the FE-SEM"

Date: March 05, 2013

Time: 4:00 p.m.

Place: Seminar Room, CNL C-310

Abstract

The new generation of Field Emission Scanning Electron Microscopes (FE-SEM) can perform high resolution imaging at incident electron beam energy below 1 keV. Images with resolution smaller than 2 nm are now guaranteed by various manufacturers. Since imaging below 1 keV allows obtaining surface details of nanomaterials and reduces beam damage for sensitive materials, it is clear that electron microscopy is now entering in a new era. With FE-SEM that can operate in the 50 eV to 30 keV range, with many images modes like conventional bulk secondary electron (SE) or backscattered electron (BSE) imaging or new scanning transmission electron microscopy (STEM) imaging of transparent materials in bright field or dark field mode, the versatility of these microscopes is obvious. Also, if we keep in mind that we can also perform quantitative x-ray microanalysis with state of the art SDD EDS detectors and crystallographic characterization of materials with EBSD detectors, FE-SEM has a very bright future and its importance in science and technology will growth faster than ever because we have now microscopes that can deliver enough current with high spatial resolution to fully exploit the advantages of low voltage scanning electron microscopy as predicted by Von Ardenne as far as 1942.

This research seminar will present new results for the characterization of various nanomaterials obtained with the new Hitachi SU - 8000 cold field FE-SEM recently acquired by the research group of Prof. Gauvin. This FE-SEM has 1 SE lower detector, 2 SE upper detectors with various modes of energy filtration, a five quadrant BSE detector, a STEM detector that works in bright field, an electron convertor that allows to use the SE lower detector for dark field STEM imaging, a 80 mm2SDD EDS X-Max detector (Oxford Instrument) and an EBSD Nordlys II System (Oxford Instrument). The maximum probe current of 40 nA allows to perform quantitative x-ray microanalysis at low voltage and also to acquire EBSD elemental maps at a faster rate, eliminating the problems of drift current issues and flashing. Results in STEM mode at 30 keV will be covered significantly.