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Durham University

GJ Russell Electron Microscopy Facility

Scanning electron microscopy

In SEM the electron beam is focused to a point and rastered over the specimen, while simultaneously collecting site-specific information. Sample preparation is relatively straightforward, e.g. bulk samples, powders, fracture surfaces. The attainable resolution is a few nanometres.

Some of the techniques available on our Hitachi SU-70 FEG SEM:

Imaging- secondary electron imaging is used to analyse topography (e.g. nanoparticles, fracture surfaces etc) while backscattered images provide pseudo-chemical contrast (good for inhomogeneous materials containing many phases, such as rocks, ceramics)

Chemistry- X-rays (EDX, WDX) are used to identify chemical elements in the sample. Compositions as small as a few atomic% can be detected at high spatial resolution.

Beam deceleration for non-conducting samples- a beam deceleration unit is available for non-conducting samples, such as polymers, biological material. This avoids the need to coat the sample.

Field free imaging for magnetic samples- magnetic samples can be imaged at high resolution in a field free environment.

Cathodoluminescence- analyses the light (visible and near-visible) emitted from the sample. Good for semiconductor devices (LEDs, photovoltaics etc) as well as minerals (defects, colour centres, growth zones etc).

Electron beam induced current- analyses the current collected by a built-in electric field, such as p-n junction. Used for quality control of semiconductor devices.

Click here for instrument specifications.