Download Scanning Electron Microscope Operation

Operating Instructions for EDAX Material Identification System
Introduction
[Note that this is the detailed description section for operating the SEM/EDAX
imaging system.]
The “EDAX” system (Figure 27) mounted on our Supra-40 Scanning Electron
Microscope is an X-Ray analysis system capable of producing an energy
spectrum from X-Rays emanating from a specimen material that is struck by
energetic electrons and analyzing the data to determine what elements are
producing the X-rays. This principle is termed Energy Dispersive (X-ray)
Spectroscopy (EDS). It is a type of X-ray Fluorescence Spectroscopy.
The EDAX X-ray detector is a Lithium Drifted Silicon detector. To avoid Li
migration under the influence of bias and temperature, the detector is chilled to
liquid nitrogen temperatures. If the liquid nitrogen evaporates and the detector
warms up above a threshold set in the software, the detector is turned off to
reduce the bias to zero. This helps prevent deterioration of sensitivity because of
the thermal and bias drift of the Lithium impurities. Filling the LN2 Dewar is a
responsibility of the Clean Room staff. If you find that the Dewar is empty, ask a
staff member to fill it. It will take at least an hour before the sensor is stable
enough to capture reliable data.
Figure 27. EDAX LN2 Dewar and pre-amplifier mounted on the Gemini electron microscope
column.
Title: Scanning Electron Microscope Operation
Author: Roger Robbins
The University of Texas at Dallas
Page 50 of 85
Date: 9/29/2015