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How can I make a single crystal silicon wafer? What are the tools needed? What is the most diffcult part? Can I make it at home or at school lab?

I am now interested on Czochralski process where you melt silicon and let it crystallize and cut afterwords.

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up vote 3 down vote accepted

Don't listen anyone. It is possible, but I have to admit - hard. Otherwise, how were first mono-crystals grown?

Initially, you may buy 'pure' silicon (pure for chemical reactions, not electronics). First of all you need to make a rod. To do that you'll need form out of material which can withstand 1600C (hard part, can't name ones at the moment), and heat Si in it using induction heating.

Induction heating might be the hardest part - but there are lots of guides around. Induction heater able to melt metal is 100% doable at home.

Once you have Si rod - you need to purify it using 'zone melting' using your induction heater. Will take ages, so you might want to make motorized thing which will move rod or heater for several days/weeks.

After that your rod is polycrystalline - which is already ok for solar cells.

For Czochralski process you may reuse again your induction heater, but the hardest part is getting clean 'form' for molten Si, as silicon is ultrapure and very easy to contaminate.

Alternatively, you may get mono-crystalline or large-grain polycrystalline Si right out of your zone heating station if you would do slow pass at the end and add seed crystal. But this might be tricky a little.

If your rod in thin enough (1-3cm) you may cut it using diamond disks, sold in usual shops. Thicker rods will require larger disks (which are not easy /cheap to buy) or 'diamond wire'.

Whole process is quite complex, but will give you lots of experience working with tough things. Dealing with silicon is much harder than Steel ;-)

PS. If you would do everything except getting seed crystals, I can send you some.

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+1 inspirational. What do you use as the slow puller for the Czochralski process? Do you counter-rotate the boule and crucible? – Richard Terrett Aug 3 '11 at 8:47
For slow pool-up - linear actuators for CNC machines + stepper motors from printers/scanners- ~20$ total at Counter rotation is too much hassle for small scale. – BarsMonster Aug 3 '11 at 8:51

No, you can not.

There are lot of ingredients which hardly may be found in school lab: extremely pure silicon, something where you melt silicon and this silicon remains pure, something which pulls this silicon crystal up slowly and carefully, a piece of crystal which you start from and so on. There is no most difficult part. The process is extremely difficult. That's why people spent few decades on this technology and wafers are still quite expensive.

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