I have some thin films samples,and I want to make sure their fermi level position.Unfortunately, I have to take them out off the chamber for not having in situ ARPES.
Dear Xuwen Zhao,
I guess it depends on how reactive are the thin films you work with. For my experience with Bi2Te3 and similar thin films, they get n-doped (the FL is pushed up) after absorbing O2, COx and other molecules present in the air.
A way to solve it is to put a protective layer on top of the thin film before taking it out from your current chamber, and then remove it by annealing once the sample is in the UHV system of the ARPES. (As an example, DOI: 10.1038/srep11595).
Dear González,
Thanks for your advice.I still have two more questions:
First,have you ever noticed the general value of ΔE(the value of FL pushed up) after exposing in the air.
Second,I am interested in electric field non-volitale tune the FL position,but I am not sure whether the process of annealing the capping layer will affect the tune.
Best Greetings,
Xuwen
Dear Xuwen Zhao,
I always work with the protective layer, as in this case, air not only dope, but also degrades the surface states of the crystals. So I have never quantified the shift of the FL.
Regarding the second question, I cannot tell in a generic way, the interaction between the protective layer and thin film is of course very dependent on the material they are made of. For instance, it is common to use Te to protect Bi2Te3 films, or Se to protect Bi2Se3 films, in order to avoid doping of a foreign element.
Best regards
Dear González,
Thanks a lot for your time.A nice conversation with you,my friend!
Best regards
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