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Sample mounting

Sample dimension​

We use standard Omicron sample holder. If the sample does not require heating, we can fix samples using silver epoxy. In case of XPS measurement, we can fix the sample using carbon- or copper-tapes. The sample dimension has to be less than 10 mm ✕ 10 mm. If the sample require heating, we need to fix the sample using metal stripes, and screw the stripes. It is better to have following sample dimensions:

  • 5 mm ✕ 10 mm
  • 10 mm ✕ 10 mm
  • Basically, one side 10 mm and other side anywhere between [5, 10] mm
  • 5 mm ✕ 5 mm
  • Arbitrary sample sizes maybe accommodated, please check with us.

Note that above sample sizes are applicable only for the samples that requires heating, or has to go inside the PLD chamber. If the sample does not require heating, any size that fits inside 10 mm ✕ 10 mm area is OK.

sample-holder

Ex-situ sample transfer​

If your thin-film is grown in another laboratory (by Molecular Beam Epitaxy or Pulsed Laser Deposition method) and you want to transfer to our ARPES chamber for measurement, we have following options:

  1. Deposit a suitable capping layer (e.g., amorphous selenium) on top of your sample surface. We can transfer such capped sample in atmosphere, and subsequently anneal at suitable temperature in our PLD chamber or on the heating stage mounted at ARPES preparation chamber.

  2. It is also possible to use a vacuum suitcase (if your growth laboratory is located within Singapore) and connect to our load-lock chamber.

Sample cleaving mechanism​

We usually cleave single crystalline samples or exfoliate layered materials in the load-lock chamber, where we can expect a vacuum better than 5 ✕10 -7 mbar. Bulk single crystalline samples can be cleaved by top-post method by attaching a pin applying strong glue (two component silver epoxy or torr seal) and later knocking out the pin by using a wobble-stick, while the layered materials can be exfoliated by attaching Kapton tape.

Sample surface can also be prepared by sputtering and annealing method.

Epoxy for sample fixing​

Samples are usually fixed using two component silver epoxy (Epotek H20E), both components should be mixed at 1 : 1 weight ratio. Hardening condition for Epotek H20E:

  • 80 deg C for 3 hrs.
  • 100 deg C for 2 hrs.
  • 120 deg C for 15 mins.
  • 150 deg C for 5 mins.
  • 175 deg C for 45 sec.

We also use Torr-seal to mount sample or fix top-post pin, where we need stronger glue. Remember torr-seal is insulating, and requires graphite coating.