1 00:00:16,132 --> 00:00:18,802 So this is, one, why this matters for today. 2 00:00:18,802 --> 00:00:21,404 So, look, I mentioned that getting red 3 00:00:21,404 --> 00:00:24,374 was hard back in the day for color TV, 4 00:00:24,374 --> 00:00:27,043 because the red phosphorus were difficult to make. 5 00:00:27,043 --> 00:00:29,479 For LEDs, it was blue. 6 00:00:29,479 --> 00:00:31,815 In fact, there was a lot of work around gallium nitride. 7 00:00:31,815 --> 00:00:33,850 Here's gallium nitride in one structure. 8 00:00:33,850 --> 00:00:35,118 Notice this. 9 00:00:35,118 --> 00:00:36,353 There's gallium nitride. 10 00:00:36,353 --> 00:00:37,687 It's not on here. 11 00:00:37,687 --> 00:00:38,321 Darn it. 12 00:00:38,321 --> 00:00:41,591 Gallium nitride in other structures have different gaps. 13 00:00:41,591 --> 00:00:42,258 Oh, there it is. 14 00:00:42,258 --> 00:00:43,760 There's one. 15 00:00:43,760 --> 00:00:45,962 But the point was they wanted blue. 16 00:00:45,962 --> 00:00:47,364 They wanted blue, and they needed 17 00:00:47,364 --> 00:00:51,101 to make a material that was both cheap to make and lasted, 18 00:00:51,101 --> 00:00:54,304 so it didn't degrade, and gave you a blue light. 19 00:00:54,304 --> 00:00:55,338 And that was really hard. 20 00:00:55,338 --> 00:00:58,975 And that's what the Nobel Prize was given for in 2014. 21 00:00:58,975 --> 00:01:02,178 Because without blue, you can't make white light. 22 00:01:02,178 --> 00:01:04,080 So there's all sorts of technologies 23 00:01:04,080 --> 00:01:07,450 you simply can't go into with LEDs until you get blue. 24 00:01:07,450 --> 00:01:08,218 How did it happen? 25 00:01:08,218 --> 00:01:11,321 It happened because of chemistry because people figured out 26 00:01:11,321 --> 00:01:14,457 how to change the how to take one element another element 27 00:01:14,457 --> 00:01:16,426 and then maybe alloy them together. 28 00:01:16,426 --> 00:01:18,828 Maybe you take gallium nitride and you alloy a little bit 29 00:01:18,828 --> 00:01:21,564 of aluminum in here. 30 00:01:21,564 --> 00:01:23,233 That means mixing it in. 31 00:01:23,233 --> 00:01:27,170 Now, all of a sudden, you've got a different band gap. 32 00:01:27,170 --> 00:01:31,107 Band gap engineering is really the centerpiece 33 00:01:31,107 --> 00:01:33,843 of the semiconductor revolution.