Sample mounting


In general, suitable samples are flat plates of max. 10×10 mm² surface area (depending on the sample holder used). The materials to be analyzed must be UHV compatible, electrically conductive and if possible homogeneous. Some other types of samples can be studied only if deposited on flat conductive substrates, e.g. evaporated or sputtered thin films, powders pressesd into indium foil etc. Samples sensitive to air exposure might be mounted in a nitrogen-filled glove bag but such option must be discussed in advance.

Several sample holders are available. The base plate, which is the same for all sample holders, is grounded, but sample can be mounted on insulated supports with electrical contacts using molybdenum M1.2 nuts. It allows sample to be heated and/or grounded or biased. The thermocouple (K-type, chromel-alumel) is available for temperature measurement. The design can be further developed depending on sample properties and user requirements (cooling, heating, thermocouple reading...).

Sample holder selection table

Sample requirements
plain mounting
Plain mounting
silicon wafer
Silicon wafers
pocket with clamps
Pocket with clamps
sapphire plates
Sapphire plates
STM type
STM type
number of samples on one holder many 1 1 1-2 1 1
can be grounded yes yes yes yes yes yes
can be biased no yes yes yes no yes
annealing up to 400 °C (700 K) no yes yes yes yes yes
annealing up to 1000 °C (1300 K) no yes yes yes no yes
measurement while annealing  ≤400 °C (700 K) no maybe no maybe yes yes
measurement while annealing  ≥400 °C (700 K) no no no no no yes
maximum annealing current 20 A 10 A 20 A 5 A 5 A

Sample mounting

  1. Mount the sample(s) on the selected holder.
  2. Check that all nuts are properly tightened. Do not exaggerate with the force in order not to break the fragile ceramic insulators.
  3. Measure the distances for the annealing and thermocouple pins according to the instructions for each sample holder.
  4. Check electrical connections (if installed):
    • sample to ground: infinity resistance, depending on the cleanliness of the ceramic insulators, several kΩ can still be fine
    • heating element contacts: low resistance, <1Ω for metals, higher for Si wafers
    • thermocouple contacts: low resistance, several Ω at maximum
    • sample to thermocouple: low resistance, several Ω at maximum
  5. Blow away any dust from the sample surface.
  6. Proceed with sample insertion.
Last Updated on Thursday, 09 March 2023 10:32