Wednesday, 22 April 2009

The day the science nearly worked

Today something quite remarkable happened. Some science, not original science I admit but something replicated from another paper, actually worked in almost the way that it was supposed to. A mere two hours of (not at all) gentle illumination under a UV laser while sitting in a crude electrochemical cell featuring potassium hydroxide and my little semiconductor wafer was etched away to reveal the precious sapphire lurking beneath.

So in this picture we see a strange parallel wall structure which somehow survived the etching. Most likely it was a scratch on the surface which caused the Gallium Nitride (the semiconductor in question) to stand up to the malevolent potassium and hydroxide ions. The point is that:
a) It looks pretty
b) The GaN itself seems to be made from two distinct layers (we're guessing it is to do with some "dopants" getting involved when the wafer was grown)
c) It's a minor success but it's the first success that I've had in eighteen months of PhD
d) That broken wasteland at the bottom of the double wall is sapphire. As in the gemstone.
e) The image was taken with a FIB (essentially you nail Gallium ions at the surface and look for the electrons which come flying off)

Saturday, 11 April 2009

Wednesday, 8 April 2009