A mini-monument, made of semiconductor laser material.  It looks to me a bit like Devil’s Tower.  It’s much, much smaller, though.  Scaling this little nano-tower (600nm high) to the height of Devil’s Tower (386m high) would be like scaling up an average-sized human (~1.7m) to about 1.1 billion meters tall.  This is, as Wolfram Alpha helpfully informs us, about 3x the distance between the earth and the moon.  Every time I do a calculation like this, it still boggles me how tiny these nanostructures are.

So, what is the nanotower doing here?  This is an image of a plasma-etched wafer of semiconductor, the sort we like to make lasers out of.  I was testing the plasma-etching process, so I was just etching simple structures into this wafer.  I did get etching - the top of the tower is where the top surface of the wafer used to be; the tower itself was formed by a tiny dust particle that happened to land on a surface, shielding a bit of the wafer from the plasma.  Unfortunately, I also got this strange fluffy surface on the wafer, signs of problems with the etching gases, or possibly contamination in the chamber.

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