I worked at a LCD factory where we first evaporate ITO on the glass, then make a pattern with photolytic process. Etching ITO can be done with battery acid. After the substrate is etched the ITO layer is still not conducting. To make ITO conducting ( and more transparent ) the substrate is baked in a oven at around 400 C Hope this helps..... Gretings
Its good to know about those teflon shaft seals. What I've done in the past at work to seal slow moving low load shafts is to have a break in the shaft with a stainless steel sheet separating the sealed and non-sealed areas and then couple them with rare earth magnets embedded in a flange on both sides. One shaft with follow the other (with a small amount of backlash).
The jar does get coated pretty well. Aluminum is pretty easy to remove with a paper towel and light scrubbing before it forms an oxide layer. I'm sure some other things are a lot more difficult.
Such an awesome video as always! I'm attempting to build a similar evaporation setup and have been using many of your vacuum vids as excellent guides. I was wondering what the black tape (and maybe material underneath tape) at the bottom of the jar is? I'm using a glass bell jar on top of an aluminum plate, granted I have awful conductance at the moment (~6mm bottleneck until a KF50 valve gets here). I cut a Viton gasket and use that between the bell jar and aluminum plate but think it might be a leak point so curious how you're sealing!
You forgot to mention that the boiling temperature drops under vacuum. This not only raises the efficiency of vapor deposition, it makes it possible to evaporate substances that have a high boiling temperature. I am building one of these as a means of plating items that can't be electroplated.
These videos are captivating beyond description. I'm going to save them and watch them with my kids some day. They remind me very much of Bill Nye, but with more deep, entertaining, technical details.
I don't know that any science/engineering educator would want to be associated with Bill Nye anymore, haha. His legacy is basically in ruin at this point.
It's basically a point source. Gravity effects should be insignificant, and once the atom or molecule is evaporated, it continues in a straight line until it hits something. The dimple normally prevents the material from being evaporated downward, but the aluminum wets the tungsten boat and crawls over the edge and then starts evaporated on the underside. It's possible to build a little box with one exit hole to control the evaporation direction.
An awesome source to browse - if you can find a decent university library is the journal 'Vacuum' - from the 1950s through the 70s. These had a heavy amount of construction-focussed articles. 'How I made a simple e-beam evaporator' and such.
If you want to drop the pressure a couple or orders of magnitude more, add another high current feed trough, and use a titanium filament with a couple of molybdenum strands for support. You do not need to melt the titanium, just get it red hot, it will sublimate. Enclose it with some aluminum foil to prevent deposition on your substrate. Lower pressure means better adhesion of the deposition material.
Sputtering is a slightly different process that uses energetic ions to knock out the substrate's molecules instead of using thermal heating. It's probably better suited for most modern processes, but requires additional equipment.
Try annealing the ITO films in vacuum; the microstructure has a strong effect on the mobility. I did some conductive oxide work about ten years ago and I don't remember having to heat the substrate during deposition. Impurities and doping also have a huge effect on conductivity.
12L14 is also known as "free machining steel". Some people have expressed concern over lead content, but it is so miniscule (0.15-0.35%) that it is really a non-issue.
Would an electrostatic field help? Like in the powder-coat process? If the bottom plate was negatively charged, and the object was positively charged, it might draw the metal atoms to it more thoroughly, like a powder-coat spray nozzle? I suppose there would be issues of conductivity, but if the voltage was high enough, even non-conductive materials should work? And to make it even more complicated, what if the metal was ionized instead of simply evaporated? Like in a tunsgten crucible with a single tungsten electrode pointing down into it, and a powerful transformer like a welding rig to strike the arc? Or a combination of these two methods, with an ionization device above the boat, like a NASA ion-drive? The metal vapor would pass up through the ionizer, and the electrostatic field would draw the ions to the object? And don't forget the dilithium crystals and flux capacitors. =-)
If you're in the Bay Area this Saturday, you may want to check out the Electronics Flea Market for variacs. I once purchased a 7.5 A unit there for around $10, and there were many vendors with similar models.
I don't know if you'll be passing through Santa Barbara any time in the near future (You're in the bay area, correct), but I'm pretty sure I have a dual-ganged 20A variac that you're welcome to have if you want. It needs some cleanup (it was a trash-find), but there's not much that can go wrong with a variac, so I'm fairly confident it'll still work fine.
Teflon is not a great insulator in a vacuum, it sublimates as well as cold flows. So if you use it as a feedthrough mechanical pressure will cause it to deform. Real feedthroughs are pretty cheap on ebay. You can also use spark plugs as feedthroughs (Non-resistor) if you are on a budget. I got some ferrofludic feedthoughs from some scrapped SEM parts.
Ben, Great work. From my pvd experience, they still make slide projection lamps. An inexpensive and controllable heater source requiring simple platinum thermal couple fed to interface into your VOM. The planetary will be a challenge, clean and with no out gas, I`ll put some thought to offer suggestion. Distance from boat to deposition substrate helpful for uniformity, more better than less.
What we used to do is put aluminum foil (a bit thicker than ordinary household foil) around the inside, so we'd just throw the foil away when it started flaking...
Ben...When I was at San Jose City College, getting my AA in Laser Tech degree, I cleaned microscope slides before coating them with Al in a vacuum, using an Ar glow-discharge or Ar-sputtering cleaning before the deposition of Aluminium, You have done most of the hard work already, have most of the equipment...why not give it Ar-sputtering cleaning a try? I really worked great on microscope slides!! Carl K6ZXU
I should do a video about this at some point. There are a lot of different thin film technologies that vary in how they create coatings. Too much to say in this comment box...
Ben, I noticed you drive a Delorean (which is awesome BTW) and was wondering if you ever thought of creating a H-Generator using H2O to increase your fuel mileage. I have been intrigued with the concept for many years now, and have personally tried making a few for an old Subaru I had with little to no success. I would be extremely grateful if you could help provide insight to over come some of the difficulties I have encountered during my experiments. Thank you for all your work in STEM research for the hobby scientist, you have inspired me to keep going searching for answers to questions many of us have, please keep making videos to inspire us to keep searching for new answers to everyday science questions.
+Casa Del Loki The oxyhydrogen generator will not help you increase mileage, you're dumping energy from the engine into the battery(loss #1) to then dump it into the generator to split water into H2 and O(loss #2) to get it back into the engine and burn it less efficently(loss #3). It is absolutely not going to work, and any people praising it are absolute nuts. You can't get more energy out of the fuel you put in by adding in water.
+Spirit I have in recent months been made aware of my error. I do however appreciate your clear and reasonable answer to my blundering mishaps. Thank you for being respectful in your response.
From what I've heard ITO can not be evaporated, because at high temperatures it returns to it's base components. I think it must be sputtered on. Could be wrong though, it was another youtube video I got that information from.
Possibly in addition to rotating the substrate through the evaporating sample, statically position the substrate say 20-30 degrees vertical, I've seen that on some of the lens coating rigs. Just a thought.
For aluminum you can use sodium hydroxide which is found in most drain cleaners and oven cleaners. Pretty much any alkaline will dissolve the aluminum in no time flat. Pick up a copy of "Vacuum Depostion of Thin Films" by Holland, pretty useful book.
I was wondering that too. I guess you should just clean it periodically with some base solvent (for aluminium). When I went to re-coad my telescope mirror, the commercial machine they had in the shop had a solid steel bell jar with a tiny illuminator style welding glass - just enough to control the evaporation. I guess it is easier to deal with residue when you have a tiny window to clean.
Is there any kind of control of deposited layer's thickness? Or just by pure theoretical calculation in order to predict how many microns or nanometers?
I was trying to find what those collar clamps were called because I wanted them for something I was working on, but didn't know the name. Now I've found them :)
I extremely needed two same sized pieces of glass, both have a coating of something that is conducive and transparent. But one of them be hydrophobic, and the other one be hydrophilic! Circle shaped glass would suit me better. Please reply
Bit late, can you add a second coat to the aluminum to seal the first coat ? Need a dump bucket inside the chamber to do multi coats. Or tubes you can open to allow other materials to be coated. Nice to watch your work.
Oh, for film thickness measurement you might be able to cut open a generic 5mhz TTL oscillator in a metal can. Mask off everything but the crystal. This goes next to the substrate. As the material deposits the frequency drops, this is how commercial dep controllers work, but this is simpler. The density and impedance of the material needs to be taken in account, the manuals for the maxtek thickness controllers list these values for a lot of common materials. I have some ideas for calibration...
Hey ben i might be wrong, but probably event though you're working under vacuum a good Heat insulation of the glass could provide a better result by minimizing temperature gradients, which may result in a better homgeneous coating. Anyway I don't think the difference would be critical, but at least slight. I think so because temperature difference could affect locally where the vapor preferably deposit Sorry for bad English
Q= ?Does the aluminum condense on the glass bell or any other object inside of the bell. If it does I have an hypothesis. When metal is in its liquid or vapor form it will react like any refrigerant, refrigerant always travels to cold, it will always condensate on the colder surface. Slightly chill the target.
Really neat stuff! Thanks for sharing your progress on this and other things that i had no idea that some one could do in their garage. Oh and do you think you need to worry about that high current in a relatively high resistance aluminum nut?
Are you flushing the vacuum chamber with an inert gas at all? Try filling and re-vacuuming with argon so the little air there is left in the chamber doesn't interfere. I'm not sure how much that influences vapor deposition, but it's a huge factor in getting a nice clean deposition with plasma.
Can you please try to make thin film solarcells ? Look into the channel of youtube user "simplifier" who succeeded to make great selfmade conductive glas very easily..!
Heyy, how to evaporate ceramic materials such as not conductive oxides? Putting them on the boat also will work ? For example Quartz is exaporatong in over 1700C so it theoretically should work but am i right ?
Ben, would it be possible to use a scanning magnetic system, the same way a television does, to control the deposition of the vaporized material? That way it could be evenly scanned across your substrate.
If that was a tungsten boat the aluminum would disololve and mix with the tungsten and make it very brittle afterward, so the aluminum have most likely gone throught the bottom and thus been deposit there as well. The tungsten will only mix with aluminium but not evaporate with it only i very small ammount. Detectable though with sensitive equipment so if this would be an issue then tungsten should not be used for evaporation of aluminum.
How are you thinking of measuring film thickness? Would be good to have a crystal monitor inside. Also I agree sputtering would be a really cool extension of this project.
I like dried fruit.I been curious about drying fruit in a negative pressure. Use your deposition chamber to dry a banana. Seems a partial vacuum would speed up the drying time.
I know this is an old subject, but do you think I could simplify this process by sandwitching donor material under a glass adopter and blasting with plasma?
You could file/mill a flat on the shaft and use a tapered grub screw to avoid marring the smooth rod surface. Do you have any videos that show the connections to your vacuum pump in detail?
Use a double o-ring seal and always keep the o-rings lubed with a vacuum grease (torrlube, krytox, or quad ring) or Ferrofluidic Seals. Also you can differential pump between the seal to maintain quality vacuum. there are several o-ring design catalogs out there and they will help you with the best design practices. Start using vacuum shielding or you will coat your chamber and quatrz crucible with all the crap you are processing. Watch out for gold, the saying is, goes everywhere.
Maybe you could adhere cling film to the inside of the glass bulb to capture stray evaporate and avoid cleaning the glass, while keeping a good view. Or maybe rather hang film on a frame, to avoid trapped air bubbles becoming enormous. HTH
You don't put motors inside the chamber, you use a feed through shaft. There is high vacuum grease with very low outgassing, but normally you don't put high speed bearings inside the chamber, only low speed without grease...
I would of milled the top of the shaft a few thousandths smaller than the bottom so you wouldnt need but a one size bigger bearing on the bottom of the shaft to stop the vaccum from wanting to pull on the shaft.
This is very impressive work ! Do you think you could do platinum-aluminid coatings on nickel alloy parts ? also to control you evaporator bath temperature have you considered using IGBTs (not very expensive on ebay) with J type thermocouples and maybe an arduino as controller ?
Following a paper I tried 500C in N2 for 30 minutes and it worked for me. The ITO was deposited using RF magnetron sputtering. Have you had any luck with post annealing Ben?
Why the V shape for the holder - could have made a simple square so only sides of the glass wouldnt be coated, doesnt need any special work, jusrt bending some wire. Copper coating could look interesting - tho the melting point alone is 400 C more.
While the gas can be in the way- it can also be used advantageously. Cooling the jar would form a barrier of still air preventing energetic materials from reaching it. At the same time additionally applying heat to the target would encourage air flow too it and perhaps aid into being able to replace heat lost to the particles from absence of a vacuum, hopefully making finding a place to settle on the substrate a little easier. Awesome video by the way as usual :)
though honestly I cannot imagine it would require much heating of the target to replace heat, the thermal conductivity of air is rather meager- but should still increase probability of hitting it.
