My stuff: silicon tower

This might be my prize material science possession. It's three pieces of silicon.

The Lego figure is just there to show some scale. I figure everybody knows how big a Lego minifigure is, especially Margaret Hamilton.

These were sitting in the back room of the original Princeton High School building before it was torn down. During the last year in the building - as we transitioned across the street - we were doing a lot of paring down, preparing to move what we needed and leave the rest behind for a public auction. This was on the shelf of another science teacher's storage room and was clearly bound for the auction. They didn't know what it was, didn't want it, didn't think it had much value.

And I grabbed it with great gusto.

I wasn't letting this one go because I know I'll likely never get another chance at it.

You can see the process of producing mono-crystalline silicon in videos I've posted before. The silicon has to be refined before this (something I got to see done outside of Butte, Montana - but where they didn't allow any photos, sadly). That results in something like the rough chunk in the front, left of the photo. This chunk is roughly small-fist sized.

That chunk - and a bunch more like it - is melted and a single silicon crystal is lowered into the rotating vat of molten silicon. The single crystal is slowly raised from the surface of the molten silicon, rotating in one direction while the vat is rotated in the opposite direction. If the conditions are just right, an single crystal of silicon is raised from the vat. That's what the tower is in the photo above. The final product was likely taller and didn't end in a flat bottom layer but rather a second tapered end.

Check out the process from about 1:00 - 3:00 in the below video.



The tower (technically a pull of silicon) would then be sliced into flat wafers that would then be etched into computer chips.

As to how Princeton High School got the silicon tower and chunks...I'm not entirely sure.

I've heard from a couple of non-PHS teachers that Cincinnati had a silicon wafer production facility that shut down and donated silicon samples to local schools, but I haven't been able to track down any information about that donation. I did find information about two silicon wafer production facilities in the Cincinnati area. One was near Maineville, but that one closed down in 2010. That's too late to fit into our timeline. The other, now known as Milacron, produced silicon wafers in the 1970s-1990s ("by 1984, the Mill had become the world's largest supplier of this type of wafer.) While I don't have any proof, that fits the timeline of a possible donation to Princeton much better. So I'm assuming we have Milacron to thank for this donation.