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Hello Saba,<br>
<br>
I have done a lot of oxide MBE growth using RF O2 plasma (similar
flow rates and pressures as you have listed) and have never had any
issue with liquid O2 in the chamber. We did quick regens of the
cryo pumps after long runs (warm the pump up to 125K while pumping
on it with a turbo) then cool it back down. This removed all the N2
and O2 from the pump. As with any gas based MBE system, you want to
have a fail safe pressure relief valve somewhere in the vacuum side
just in case the power fails or the pumps goes out while you are
warming up the cryo panels. I have had a lot of gas come off the
panels during the warm up process, but nothing that created a
pressure spike. <br>
<br>
If you have a mass spec on the chamber, record the N2 and O2 spectra
during the warm up cycle and see how much evolves.<br>
<br>
Best Regards,<br>
Brent<br>
-- <br>
Brent P. Gila, PhD.<br>
Director of the Nanoscale Research Facility<br>
University of Florida<br>
1041 Center Drive<br>
Gainesville, Florida 32611<br>
<a class="moz-txt-link-freetext" href="Tel:352-273-2245">Tel:352-273-2245</a>, Fax:352-846-2877<br>
email: <a class="moz-txt-link-abbreviated" href="mailto:bgila@ufl.edu">bgila@ufl.edu</a><br>
<br>
<br>
<div class="moz-cite-prefix">On 2/26/2020 1:23 PM, Saba Sadeghi
wrote:<br>
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<p>Dear all,<br>
</p>
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I have a question about MBE systems that are used
for metal-oxide growth. </p>
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In our MBE system we use oxygen flow rate of 0.3 - 0.4 sccm,
which leaves the chamber pressure at about 1E-5 Torr.</p>
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The chamber incorporated LN2 cooling shrouds. My question
is that do you think that there is any concern regrading
liquefaction of oxygen on the chamber's wall, that might end
up dripping down the walls, evaporating and causing a
pressure burst.</p>
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I have not encountered the problem yet, but I was wondering
if over time, and for long growth time this might become an
issue. Has anyone encountered this issue before? </p>
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Any input is much appreciated,</p>
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Best,</p>
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