I suggest taking a look at the discussion here https://www.researchgate.net/post/Why_can_I_get_no_RHEED_oscillation/1

Although the question is different, some of the suggestions apply here as well.

Thanks Lior

I am still trying to find the RHEED patterns.

Dear Estiak,

do you have the possibility to rotate the sample in-plane along 360°? Sometimes the angles where RHEED patterns can be seen are quite sharp.

Which orientation does your wafer have? Do you know how it is oriented with respect to the electron beam, i.e. in which angular orientation you can expect patterns?

How long did you heat the substrate?

What about the vacuum in your chamber, which order of magnitude do you reach?

Best,

  Andrea