Energy Resolution
The spherical sector analyser on MICROLAB 350 (or ESCALAB 250 fitted with a FEG 1000 electron gun) allows the user to select the most appropriate energy resolution for any Auger analysis.
High resolution allows
- Interferences to be resolved
- Chemical states of the same element to be differentiated
- Doping types of semiconductors to be imaged
In this case the high resolution is being used to distinguish two types of silicon (n-type and p-type). The energy difference is only 0.6eV.
The spectrum shows the energy difference in the silicon Auger peak. Using this difference images can be constructed from the p-type and n-type material, an overlay of such images is shown here.
Alternatively, a sputter profile may be constructed from a specimen of doped silicon. The non-linear least squares fitting feature of the Advantage software can then be used to construct a peak shift profile as a function of depth.
The example shown here is from a silicon wafer doped with phosphorus at 180keV at a dose of 10e15 atoms per square cm. |
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