Samples and sample holder for the SPELEEM microscope
The image below shows the sample holder (cartridge) used in SPELEEM. The sample is fixed into the sample holder with a Mo cap after gentle tightening of four symmetrically placed M2 screws. In both the preparation chamber and the main chamber, the sample can be heated to 400 °C (radiative heating) with a filament built in the sample holder, or be heated to even higher temperatures (1300-1500 °C) by e-beam bombardment. For a rough temperature measurement, there is a type-C thermocouple (W5%Re/W26%Re) spot-welded on the Mo ring under the sample. For a more accurate measurement, an infrared pyrometer is available.
General information on sample feasibility
1) Samples for measurements in SPELEEM must be conductive, otherwise charging problems occur hindering the measurements.
2) Samples must be flat without any macro- or micro-size tips, as they may cause significant field emissions and eventually deleterious arcing.
3) The size of the sample should generally not be less than 5×5 mm2 and not more than 10×10 mm2 (square) or Φ14 mm (disc). The maximum thickness is 2.5 mm. Caps with various openings (from 4 to 10 mm) are available.
Note for non-standard samples:
- In some special cases, very small samples (down to 2 mm in diameter) can be loaded and studied at the expense of the spatial resolution
- Non-conductive samples can be measured with a specially prepared mask (metallic mesh)
- In situ cleavage is also possible if it produces a smooth surface
- In special cases, samples with larger thickness (> 2.5 mm) can be measured but they must be notified to the beamline staff well in advance
- All non-standard samples must be negotiated with the beam line scientist well in advance!
The inspection of the sample surface under the optical microscope is recommended before loading the sample in the UHV chamber (please see Preparation Laboratory section).