SupaVillain
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Will Aluminum chamber body react with these?
If I am to build an atomic layer deposition chamber out of either aluminum or stainless steel... Will aluminum react with any of these bolded
chemicals? obviously i prefer aluminum for cost minimization, but it will be so thin really that I may just do stainless. I already have a
sheet of aluminum though...
"A custom-built hot-wall ALD reactor was used to grow
Zn(O,S) and Al-incorporated Zn(O,S) films. Films were
grown at a deposition temperature of 120 C in closed valve
mode. The precursors used were diethylzinc (DEZ,
Zn(C2H5)2), deionized H2O, a gas mixture of 4% H2S in N2,
and trimethylaluminum (TMA, Al(CH3)3) for the zinc, oxygen,
sulfur, and aluminum sources, respectively. Purified N2
was used as the purging gas. All of the precursors were kept
at room temperature. The exposures used for each dose of
DEZ, H2O, H2S, and TMA are estimated to be approximately
0.13, 0.15, 6.50, and 0.22 Torrs, respectively. The
ALD sequence for Zn(O,S) was (DEZ/N2/H2O/N2) m þ
(DEZ/N2/H2S/N2) 1, where the stoichiometry was varied
by tailoring m for different sulfur incorporation into the
films. The ALD sequence for Al-incorporated Zn(O,S) was
(DEZ/N2/H2O/N2) m þ (DEZ/N2/H2S/N2) 1 þ (DEZ/
N2/H2O/N2) (m–1) þ (DEZ/N2/TMA/N2/H2O/N2) 1 þ
(DEZ/N2/H2S/N2) 1, where aluminum was incorporated
into every other Zn(O,S) ALD cycle"
http://www.diva-portal.org/smash/get/diva2:52367/FULLTEXT01....
[Edited on 15-8-2015 by SupaVillain]
Oh.
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gdflp
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No, argon will not react with any of those. I don't think that a situation exists in which nitrogen is inert to the environment, but argon is not.
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SupaVillain
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Thank you, I think they normally use ultrapure nitrogen simply because normal air, which is wet, should be kept out, and it's usually cheaper than
argon, but not for my current case
Oh.
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Nicodem
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Thread Moved
14-8-2015 at 14:50 |
AJKOER
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Maybe, as perhaps an electrochemical reaction is possible. For example, you apparently have many of the workings for a galvanic cell as:
1. You have two different metals, Zn and Al, or a metal and oxygen.
2. You have aqueous H2S which could undergo a oxidation-reduction reaction.
3. You have H2O and the only possible missing ingredient is a good electrolyte (normally, something like NaCl or ZnCl2, but you may have some
impurities that could contribute to a functioning poor electrolyte).
Note, low concentration levels are not a guarantee against an unwanted electrochemical reaction here.
[Edited on 15-8-2015 by AJKOER]
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SupaVillain
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wrong link, whoops
http://faculty.chemistry.harvard.edu/files/gordon/files/ald....
Oh.
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unionised
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Quote: Originally posted by AJKOER  | Maybe, as perhaps an electrochemical reaction is possible. For example, you apparently have many of the workings for a galvanic cell as:
1. You have two different metals, Zn and Al, or a metal and oxygen.
2. You have aqueous H2S which could undergo a oxidation-reduction reaction.
3. You have H2O and the only possible missing ingredient is a good electrolyte (normally, something like NaCl or ZnCl2, but you may have some
impurities that could contribute to a functioning poor electrolyte).
Note, low concentration levels are not a guarantee against an unwanted electrochemical reaction here.
[Edited on 15-8-2015 by AJKOER] |
I think the important thing for electrolysis that's missing is a liquid phase.
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AJKOER
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I agree, not much of a liquid phase, but a possible counter argument based on Wikipedia's comment on an Aluminum-air battery, as an example, (please
see https://en.m.wikipedia.org/wiki/Aluminium–air_battery ) is that all you need is a "porous hydrophobic PTFE film that prevents electrolyte
leakage", with still an outstanding question as to whether, in this case, an effective electrolyte is ever present. Note, the process apparently
proceeds, to quote, "The exposures used for each dose of DEZ, H2O, H2S, and TMA are estimated to be approximately 0.13, 0.15, 6.50, and 0.22 Torrs,
respectively."
My basic point is that if things don't proceed as anticipiated, I would recommend employing something other than Aluminum (which, I suspect, is not
even pure Al but more likely an alloy for added strength). Note, this reference cites the use of glass, see http://pubs.acs.org/doi/abs/10.1021/cm00023a015
[Edit] For clarity, I claim the possible presence of some metallic Zinc as the more reactive Aluminum could become plated with Zn from the ZnOxSy
(where x+y =1). However, reaction time may mitigate this issue, but if not and any elemental sulfur is also released (as I doubt the creation of
Aluminum oxysulfide), then a whole corresponding set of chemical (and electrochemical) reactions based on sulfur could be observed as well.
[Edited on 16-8-2015 by AJKOER]
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SupaVillain
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If you're interested, take a look at this video
https://www.youtube.com/watch?v=x-YRl0U_u2c
basically, cheap glass sheet from home improvement stores, on top of a short height stainless steel frying pan makes a lot of sense to me, and i'm
thinking the valve openings should let the gas across the top of the substrate, as well as the nitrogen, while the vacuum valve (outlet) should be in
the opposite position of the inlet gas valves.
.....while controlling the (10 millisecond?) time interval gaseous precursor valves with a computer algorithm via microcontroller like an arduino,
that switches on and off some simple electromagnet solenoid valves.
basically i would write down in the programming (pseudocode) something representative of this:
1st step
open vacuum valve until 0.65 torr
then close vacuum valve
open valve DEZ for 0.01 second
then close valve DEZ
open vacuum valve for 1 second
then close vacuum valve
open N2 valve for 0.01 second
then close N2 valve
2nd step
open vacuum valve until 0.15 torr
then close vacuum valve
open valve H2O for 0.01 second
then close valve H2O
open vacuum valve 1 for 1 second
then close vacuum valve
open N2 valve for 0.01 second
then close N2 valve
3rd step
open vacuum valve until 6.5 torr
then close vacuum valve
open valve H2S for 0.01 second
then close valve H2S
open vacuum valve for 1 second
then close vacuum valve
open N2 valve for 0.01 second
then close N2 valve
4th step
open vacuum valve until 0.22 torr
then close vacuum valve
open valve TMA for 0.01 second
then close valve TMA
open vacuum valve for 1 second
then close vacuum valve
open N2 valve for 0.01 second
then close N2 valve
but i've read somewhere i think this process is looped 70 times or so but it doesn't take very long because it's mostly very short split second pulses
of gases and vacuum one after the other
Oh.
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