3 ms·
Does anyone know why the P and N regions conveniently show up as different colors on the photo? Is this due to different oxide thickness?
by sigterm 12y ago
Does anyone know why the P and N regions conveniently show up as different colors on the photo? Is this due to different oxide thickness?
- etimberg 12y agoInteresting question! I don't know the actual reason, but if I had to wager a guess I'd say that it's due to the different types of doping of the silicon. Some searching did indicate that is what gives some types of gemstones their colour (rubies for instance receive their red colour from chromium impurities distributed throughout the lattice structure http://en.wikipedia.org/wiki/Dopant#Examples http://en.wikipedia.org/wiki/Dopant#Examples). It seems plausible, but there is probably a more accurate answer out there.
- marcosdumay 12y agoOne makes the entire dye with a kind of dopant, creates a oxide layer above it, and remove the oxide where it should be doped again. Thus, I'd guess the difference in color is due to the different thickness of the oxide layer.
- analog31 12y agoThickness makes sense due to the same phenomenon as Newton's rings.